Pit was first depicted with blue eyes and a laurel crown in promotional artwork for Kid Icarus: Of Myths and Monsters, which was not released in Japan until 2012. If the eye color and crown of Pit's design in 2008's Super Smash Bros. Brawl was influenced by Of Myths and Monsters and wasn't simply a coincidence, that would make it the first and so far only instance of Super Smash Bros. referencing content from a game without any kind of Japanese release at the time within gameplay, and shared with a sticker originating from Of Myths and Monsters as the first representation of a game without a Japanese release whatsoever outside of the Chronicle (which is also technically tied with trophies in the same game from Elite Beat Agents, a heavily modified localization of Osu! Tatakae! Ouendan).

Donkey Kong's sprite on 75M in Super Smash Bros. Brawl and Super Smash Bros. for Wii U has a tan skin tone, which is different from DK's paler sprite in either the NES or arcade versions of Donkey Kong. This appears to be the result of Nintendo using an image of the game's arcade version originating from a Japanese retro gaming fan site called Muu-World as reference material, as that image seems to have a color error that makes DK appear tan. The English-language fan wiki Super Mario Wiki has been hosting a different Donkey Kong screenshot with the same error on its page for the game since 2005, and the source of the error as well as several of the images featuring it (including the Mario Wiki screenshot) is currently unknown. It also gives DK a coincidental resemblance to the appearance on the box art for NES Donkey Kong and in-game in Atarisoft's Commodore 64 Donkey Kong. This was fixed for Super Smash Bros. Ultimate.

Upon the release of Super Smash Bros. Brawl, many Wario fans were disappointed and shocked to see that his moveset had a powerful farting attack, something that seemed unprecedented for the character to fans in the US. In Japan, Wario's association with toilet humor in promotional material dates back to Wario Land II at least. The marketing for Wario Land 4 is arguably when the gross-out humor could be considered most prominent, with the game having golden poop stickers included in its manual, and the official Japanese website going into immense detail on the size and shape of Wario's fecal matter:


Up until Brawl's release, Wario had not been associated with vulgar humor that much within actual games, and the only glimpses US audiences would've received of Wario's slobbish side in marketing would have been in animated commercials where he was animated to have saliva dripping out of his mouth (something that could be easily disregarded given that Nintendo used gross-out gags to market most of their titles in the US at the time, even for less edgy characters such as Kirby and Yoshi) and - by an extreme stretch - a subplot in WarioWare: Touched! revolving around Wario's bad oral hygiene. Following Brawl, farting would be cemented as one of Wario's signature abilities in a variety of Mario games.

The Landmaster's appearance as Fox, Falco and Wolf's Final Smashes in Super Smash Bros. Brawl and Super Smash Bros. for Nintendo 3DS and Wii U is a composite of its appearances from Star Fox 64 and Star Fox Assault, maintaining the sharp and futuristic appearance it had in the latter, but still retaining traditional tank treads as seen in the former.

This particular design would eventually be implemented into the Star Fox series proper, beginning with the Landmaster's appearance in Star Fox 64 3D, and would be used again in Star Fox Zero.

The English manual and prologue for Star Fox Adventures implies a bigger backstory for Krystal, in that she's the sole remaining survivor of her doomed home planet, "Cerinia", and that she's been roaming the galaxy in search of answers for the truth of her family's death, until she receives a distress call from Dinosaur Planet. With how the manual states that Krystal "may finally be drawing closer to the truth" behind her parents' and planet's destruction, it seems Rare was loosely implying that Andross, who turns out to be the real villain of Star Fox Adventures and thus the culprit behind Dinosaur Planet's woes, was responsible for Cerinia's destruction. Krystal even says "It's you!" right before Andross imprisons her in the crystal at the top of Krazoa Palace.

However, it would seem the Japanese localization for Star Fox Adventures would completely eschew this backstory, removing all mention of Cerinia and as well as Krystal's dead parents. The Japanese prologue was even heavily simplified to this:


The Japanese website even states that "it is not known what her purpose is", which flies directly in the face of Rare's original story for her, that explicitly states that she was searching for the truth of Cerinia's destruction. To add more insult to injury, there isn't even any Japanese subtitle presented when Krystal gets knocked into the crystal by Andross in Krazoa Palace.

Curiously, the Japanese localization of Star Fox Adventures also heavily emphasizes Krystal having telepathic abilities, much more so than in the English version. This is noteworthy because neither Star Fox Assault or Star Fox Command, the next two story follows up to Star Fox Adventures that were developed and written in Japan, made any sort of mention of Cerinia. Star Fox Assault however would hugely emphasize her telepathic abilities, and its manual even describe Krystal the same way the Japanese version of Star Fox Adventures does, just as "a mysterious telepathic woman". This also applies to her trophies in Super Smash Bros. Brawl and Super Smash Bros. for Nintendo 3DS and Wii U that once again make no reference to Cerinia. It's very clear that the developers and writers behind Assault, Command and Smash Bros. in Japan were using the Japanese version of Star Fox Adventures as a reference, as opposed to the English version.

All in all, it would seem Nintendo of Japan had their own differing vision of what Krystal's character was from Rare, that being mostly just as a telepathic woman with a mysterious background, as opposed to Rare's original backstory of her being the lone survivor of her kind.

As of Super Smash Bros. Ultimate in 2018, Shadow the Hedgehog is the only third-party Assist Trophy to appear in every Super Smash Bros. game since the introduction of Assist Trophies in Super Smash Bros. Brawl in 2008.

A voice line of Snake saying "There!" can be found in the files for Super Smash Bros. Brawl. While it remains unused in this game, it would later be used for when Snake plants a C4 explosive in Super Smash Bros. Ultimate.

In the files for both games are unused animations of Diddy Kong laughing. The file names in Brawl suggest that it would’ve been used when using the Banana Peel down special.

Like its predecessor, Super Smash Bros. Melee, The game was originally supposed to include alternate trophies along side their regular trophies for the playable characters. No icons nor preview images exist for any of the trophies.

There is an unused model of Luigi with blue clothing which differs quite a bit from both Luigi's and every other character's model. One interesting difference is that this costume has its shadow model integrated into the model itself, rather than having it as a separate model.

In this version of the Yoshi's Island stage, if a player's shield breaks while they are standing on one of the sloped parts at the end of the main platform, when they land they will roll off the stage, canceling the shield break stun. This allows the to immediately regain consciousness and move much sooner than intended.

Wolf, Jigglypuff, and Toon Link were not involved with the plot of the Subspace Emissary due to them being close to not appearing in the final roster.

Wolf barely made it into Super Smash Bros. Brawl due to time constraints. He was added to the game because of popular demand, and because he was an easy character to create by sharing a fair amount of attacks and animations with Fox and Falco.

The stadium in Home-Run Contest is actually a loop. After 40,000 ft, it will go back to zero.

In the Subspace Emissary, there were plans to include a scene where Meta Knight still had control of the Halberd, before being attacked and losing the ship to Tabuu. This scene was removed from the final game.

Super Smash Bros Brawl was Samus's first appearence that featured voice acting, as Zero Suit Samus has several spoken taunts. Before this, only three games had had her say any lines: Super Metroid, Metroid Fusion, and Metroid: Zero Mission; these lines were only in text format and were unspoken.

The Mario Circuit stage has its entire stage modeled out. It even has some blocks and trees in the distance.

Smash Bros. Director, Masahiro Sakurai, has stated that Shigeru Miyamoto had approached him about adding Pac-Man into Smash Bros Brawl. Sakurai imagined Miyamoto inferring to adding Pac-Man in his original 2D form to the game, and that the idea would be "too farfetched".

The Japanese release exclusively includes a 5-minute demo of Mother 2 (known as EarthBound in West) and a 3-minute demo of "Fire Emblem: Monsho no Nazo" within the Masterpieces menu.

There's is an unused enemy called Mizzo which is never found in the Subspace emissary except during the enemy display room inside the Halberd. It appears to be an orb with arms and legs sticking out, surrounded by wind. However, a trophy exists for this enemy which will spawn randomly wherever trophies can spawn. The trophy description references this enemy's absence.