Originally, an island known as Shipwreck Cove (designed by producer Jason Kim) was going to appear in the game, with much of its data remaining in the game files. Despite how finished the remaining materials look, designer Brian Kaiser claimed that the developers did not get very far into production on it. The full level layout can be found in the unused data, meaning that the island can be stitched together using several models. Four NPCs were intended to appear on the island, those being Vice Admiral Morgan, Neema, Theodore, and Mira (who would later be reworked into Mira Cull, the daughter of series regular Barney Cull in MySims SkyHeroes; it's unknown if she was intended to be related to him in this game). Additionally, five music tracks related to the island are also in the game files, the names of which suggest that planned landmarks for the island include a Pirate Lighthouse, Mira's House, and Neema's Shack.
The Flame Shield was originally intended to appear alongside the Aqua and Thunder Shields, but it was removed due to it being too similar to the Thunder Shield.
In a 2002 developer interview archived by the now-defunct blog GSLA, director Yoshiaki Koizumi revealed that the game's staff originally came up with ten different nozzles for FLUDD, devising new ones for each possible situation Mario might encounter. However, this was reduced to three to avoid similarities to the gameplay style of The Legend of Zelda series. Some remnants of this larger quantity can be found in the final game's data, which includes an unused model for a Yoshi head nozzle and parameters for a sniper nozzle. While the former's properties are unknown beyond its appearance (with its model lacking any associated animations), the latter would have been 100 times more powerful than the Squirt Nozzle and would've had a significantly larger hitbox. However, it also would've required Mario to charge it like the Rocket Nozzle and Turbo Nozzle.
The Dark Eternal Champion has unused frames of animation left over in the game's files. It is unknown if these were meant for an alternate victory animation or a scrapped special move.
According to the game's director, John Johanas, Chai's hospital gown from Track 1 was meant to be an unlockable costume. However, the physics of the costume didn't respond well to Chai's moves and thus got scrapped.
According to developer Peter Molyneux in a 2019 interview, the different speed stats for the game's vehicles are entirely for show, and they all drive at the same speed. The lack of different vehicle speeds was due to time constraints stemming from a roughly six and a half week development period, but just seeing supposedly different speed stats when selecting a vehicle seemed to fool critics and players into thinking they were different at the time. Molyneux credits this concession for allowing Bullfrog Productions to focus more time into developing Dungeon Keeper, which would not release until nearly two years after Hi-Octane came out. It's rumored that early builds of Hi-Octane did have different vehicle speeds that were slowly worked on by the development team in their downtime as a side project. Molyneux claimed that this rumor was likely true, but that due to the same time constraints, they could not have made enough progress for the vehicle changes to be implemented into the final game.
Several additional characters were planned to appear in the game, but were scrapped in order to keep the game's plot easier to understand. This includes the presence of a "Space Broadcasting Censorship Bureau", who would interrupt broadcasts that were deemed unsuitable (and whom Pine was originally going to be a member of alongside her backups Sexy 1 and 2, taking issue with Ulala's exposing outfit), a narcissistic reporter from Channel 777 named "Gold Kinpicano", and a different main antagonist tentatively referred to as the "Dark Dancing Demon Lord", whose goal was to invade the entire universe with dance.
Before the Earth was implemented as a level selection screen, levels in Tornado Outbreak were originally displayed on a 2D world map and rendered entirely with Adobe Flash.
There is an unused title screen in the Metal Slug bootleg game Terrifying 9/11 that suggests it was originally going to be released as a straightforward bootleg version of Metal Slug instead of a bad-taste cash-in on the September 11th attacks.
In the prototype of Hotel Mario, walking Toads are used as Super Mushrooms and 1-Up collectables. The final game changes these Toad sprites to bouncing mushrooms, but the manual still refers to them as Toads.
Capcom offered a demo CD based upon a beta build of the game as a pre-release promo. The entire build was on the disk, with a "time trial" style of gameplay lasting 45 minutes before exiting the game. A code was eventually worked out, utilizing a GameShark cheat device in order to disable the time trial demo's timer, enabling complete access to this earlier version. A list of notable differences compared to the retail release have been noted as a result, and Capcom would never release a time trial demo disc again.
The unpatched release of Version 0.10 contains unused data for an event on Mars called "階段←↓". Re-enabling this event opens an alternate, invisible entrance to the Martian underground, to the left of the hole that leads to it in the final game; however, the map's collision data prevents Madotsuki from actually using it without the aid of further cheats.
Furthermore, the game contains unused graphics for a stairway that matches the visuals of the Martian surface, and the Martian underground features several flights of stairs at the beginning. This indicates that the underground was originally meant to be accessed via the unused stairway rather than needing Madotsuki to activate the Midget effect, with the summit's layout being changed concurrently with the altered entrance. The Yumesyuusei Patch and all releases based on it (including the official English release) remove the data for 階段←↓, though the unused stair tiles are unaffected.
Additionally, the game's code contains tiles for doors on the walls of the Martian underground, indicating that the sub-area was originally planned to feature multiple rooms rather than just one. This, combined with the unused alternate entrance, implies that Kikiyama had to leave Mars incomplete for unknown reasons, polishing up what was already completed late into Version 0.10's development.
Within all available builds of the game are sprites for three possible effects that were never implemented. One set of sprites depicts Madotsuki blindfolded, another depicts a grayscale version of her similar to the "ghost" found in Mini Hell, and a third depicts 8-bit versions of the "crick in the neck," which in the final game is instead an event where Madotsuki randomly wakes up with her head stuck facing leftward. Of note is that Versions 0.07 to 0.09 additionally feature sprites for blindfolded and grayscale Madotsuki pinching herself awake; Version 0.10 overwrites them with the "active" sprites for the Spirit Headband effect.
Additionally, the game's data contains an unused mugshot depicting what appears to be an early iteration of the Spirit Headband effect, in which Madotsuki turns into a hitodama (a disembodied soul which appears as a floating ball of fire, comparable to a will-o'-the-wisp in many Western cultures) rather than becoming invisible. A full set of sprites for this version is also present in Version 0.04's data, showing that rather than turning invisible, pressing the 1 key would've simply changed the fire's color.
The game contains data for a second party member, despite the fact that Madotsuki is alone in standard gameplay. Using RPG Maker 2003's debugging tools to add this figure to Madotsuki's party shows that it does not have any sprites or even a name. However, various changes occur to the game's world, indicating that Kikiyama most likely used this for testing purposes:
• Almost all Toriningen are despawned; the only exceptions are the one in the Mall who changes the menu's palette when spoken to and the group throwing a party in the wilderness. • The top-left cupboard in both versions of the Guillotine Room disappears. However, it can still be interacted with: pressing Z or Enter when standing where it normally would be transports Madotsuki to a random cupboard in the Number World, as if she had used one of the randomly generated exit cupboards. Returning to the Guillotine Room restores the top-left cupboard to its normal position. • Movement is disabled upon waking up. • The Witch's Flight event can be accessed by walking off the top-right corner of the Mall's rooftop, regardless of whether or not Madotsuki has the Witch effect equipped and active. • An unused parallax background (named ネオン背景.xyz in the game's files) is enabled in Neon World, which normally has a solid black backdrop in Version 0.10 and all available early builds. This background, which depicts a series of ripples distorting a group of red, blue, and green lights, does not scroll correctly, only showing the top-left corner of it. Notably, this is the only unused background in the final game.
The notion that this invisible party member was used as a debugging tool is further bolstered by the presence of three similar extra party members (which also have no graphics or names) in Version 0.06. In that earlier build, Madotsuki is internally listed as the fourth party member; enabling the first one adds NASU to the game's debug map, though both that version and the one in Madotsuki's room will not progress past the title screen.
In all recovered early builds of the game, the Fatten effect was provided by a funhouse mirror hidden in the large red maze (colloquially known as Hell). In Version 0.10, the mirror is removed and the effect is instead obtained by interacting with a tall, flashing humanoid (colloquially known as Strober) in the Docks B, and the portion of Hell where the mirror was once located is now empty. Incidentally, the Docks B is only accessible through Hell, preserving the association between the latter area and the effect.
Despite the mirror being removed from the normal course of play in the final build, it is still present in a debug room hidden in the game's code, functioning as it did in earlier versions. However, in the official English release, the text that appears when interacting with it, "★ふとる★", is corrupted due to it not being translated.
Within the files for the Version 0.04 build are cached thumbnails depicting screenshots from a cut soccer minigame called Severed Head PK, which, per its name, would've used severed heads as balls. Despite their small size, the thumbnails are legible enough to understand what they depict: one shows a title screen, one shows a player select screen, and one shows actual gameplay. Additionally, all three images feature a much cruder art style than either the main game or NASU, the minigame ultimately added in Version 0.05. Of note is that like Severed Head PK, NASU takes place in a green field beneath a black sky and prominently features bright red assets (hills, text, and the title logo in Severed Head PK; the player character, clouds, and a strobe effect in NASU).
Given that NASU is preceded by a game selection menu with only two options present – "NASU" and "Quit Game" (the latter of which simply closes the menu) – it is unknown if Kikiyama intended to reincorporate Severed Head PK as an additional option.
In the release build of Super Mario Maker, there were text strings relating to 13 unused Mystery Mushroom costumes: • BabyMario • BalloonFight • EGadd • GoldenRetri (presumably short for "golden retriever") • MarioUs (presumably Mario's appearance from what is known in Japan as Super Mario Bros. USA) • Mashiko (Japanese name of Mary O.) • MrSaturn (from EarthBound) • Muncher • Nabbit • Popo • Tetris • WindowsLogo
Baby Mario, Balloon Fighter, E. Gadd, Mary O., Mr. Saturn, and Nabbit would eventually be added in updates, as would an Ice Climbers costume featuring Popo alongside his friend Nana, while a power-up that turns Mario into his Super Mario Bros. 2 self would be introduced in an update to Super Mario Maker 2.
The most notable names are "Tetris" and "WindowsLogo", two non-Nintendo franchises that otherwise go unrepresented in Super Mario Maker. Tetris was formerly published on handheld and home consoles by Nintendo between the 1980s-1990s, and has been featured through music and Spirits in the Super Smash Bros. series, which is used as the basis for Super Mario Maker's base-game third party costume selection. WindowsLogo seems to be some kind of remnant of a Microsoft Windows operating environment being used to develop the game, as Nintendo has never been involved with the Windows line of software.
The box arts of Japanese Crash Bandicoot localizations have historically used a redesign for Crash with larger eyes. This has been done for all games except for the "Titans" sub-series, which had its own distinct Crash design, and the Toys for Bob-developed games.
However, the only games that feature the design in-game for the Japanese localizations are the Japanese-developed Crash Boom Bang!, and Crash Tag Team Racing, which had a skin system that allowed Japanese Crash to appear abroad as well. A good chunk of Crash's costumes in Crash Tag Team Racing also got Japanese versions, though these combination costumes were not included in the Western release.
In the September 14, 2023 edition of the Undertale/Deltarune newsletter, Toby Fox revealed that a stealth sequence was planned for Chapter 3, only to be cut partway through development due to his dissatisfaction with it, stating that "a mechanic which basically just makes you move slower isn't necessarily fun." To compensate for the segment's removal, Fox included an MP3 file of the music that was composed for it, as the song would not be featured in the final game.
The Flame Shield was originally intended to appear alongside the Aqua and Thunder Shields, but it was removed due to it being too similar to the Thunder Shield.
In a 2002 developer interview archived by the now-defunct blog GSLA, director Yoshiaki Koizumi revealed that the game's staff originally came up with ten different nozzles for FLUDD, devising new ones for each possible situation Mario might encounter. However, this was reduced to three to avoid similarities to the gameplay style of The Legend of Zelda series. Some remnants of this larger quantity can be found in the final game's data, which includes an unused model for a Yoshi head nozzle and parameters for a sniper nozzle. While the former's properties are unknown beyond its appearance (with its model lacking any associated animations), the latter would have been 100 times more powerful than the Squirt Nozzle and would've had a significantly larger hitbox. However, it also would've required Mario to charge it like the Rocket Nozzle and Turbo Nozzle.
The Dark Eternal Champion has unused frames of animation left over in the game's files. It is unknown if these were meant for an alternate victory animation or a scrapped special move.
Before the Earth was implemented as a level selection screen, levels in Tornado Outbreak were originally displayed on a 2D world map and rendered entirely with Adobe Flash.
There is an unused title screen in the Metal Slug bootleg game Terrifying 9/11 that suggests it was originally going to be released as a straightforward bootleg version of Metal Slug instead of a bad-taste cash-in on the September 11th attacks.
In the prototype of Hotel Mario, walking Toads are used as Super Mushrooms and 1-Up collectables. The final game changes these Toad sprites to bouncing mushrooms, but the manual still refers to them as Toads.
The unpatched release of Version 0.10 contains unused data for an event on Mars called "階段←↓". Re-enabling this event opens an alternate, invisible entrance to the Martian underground, to the left of the hole that leads to it in the final game; however, the map's collision data prevents Madotsuki from actually using it without the aid of further cheats.
The game contains data for a second party member, despite the fact that Madotsuki is alone in standard gameplay. Using RPG Maker 2003's debugging tools to add this figure to Madotsuki's party shows that it does not have any sprites or even a name. However, various changes occur to the game's world, indicating that Kikiyama most likely used this for testing purposes:
In all recovered early builds of the game, the Fatten effect was provided by a funhouse mirror hidden in the large red maze (colloquially known as Hell). In Version 0.10, the mirror is removed and the effect is instead obtained by interacting with a tall, flashing humanoid (colloquially known as Strober) in the Docks B, and the portion of Hell where the mirror was once located is now empty. Incidentally, the Docks B is only accessible through Hell, preserving the association between the latter area and the effect.
Within the files for the Version 0.04 build are cached thumbnails depicting screenshots from a cut soccer minigame called Severed Head PK, which, per its name, would've used severed heads as balls. Despite their small size, the thumbnails are legible enough to understand what they depict: one shows a title screen, one shows a player select screen, and one shows actual gameplay. Additionally, all three images feature a much cruder art style than either the main game or NASU, the minigame ultimately added in Version 0.05. Of note is that like Severed Head PK, NASU takes place in a green field beneath a black sky and prominently features bright red assets (hills, text, and the title logo in Severed Head PK; the player character, clouds, and a strobe effect in NASU).
The box arts of Japanese Crash Bandicoot localizations have historically used a redesign for Crash with larger eyes. This has been done for all games except for the "Titans" sub-series, which had its own distinct Crash design, and the Toys for Bob-developed games.
In the September 14, 2023 edition of the Undertale/Deltarune newsletter, Toby Fox revealed that a stealth sequence was planned for Chapter 3, only to be cut partway through development due to his dissatisfaction with it, stating that "a mechanic which basically just makes you move slower isn't necessarily fun." To compensate for the segment's removal, Fox included an MP3 file of the music that was composed for it, as the song would not be featured in the final game.