According to composer Grant Kirkhope, the DK Rap was written as a joke song that ended up being interpreted by audiences as a serious attempt at writing hip-hop. Consequently, he expressed confusion at the tongue-in-cheek cult following the song picked up decades later, noting that "bizarrely, this became its own thing now."

Diddy Kong Racing DS is somewhat infamous for introducing the newly redesigned Tiny Kong, who despite being originally conceived by Rare as Dixie Kong's younger sister in Donkey Kong 64, is now depicted as a taller teenager. This design would carry over into future titles such as Donkey Kong Barrel Blast and Mario Super Sluggers.

Contrary to popular belief, as revealed on a December 20, 2007 edition of Rare's Scribes, the decision to redesign Tiny into a teenager was not Rare's call, but Nintendo's, which is appropriate considering Nintendo has retained full ownership of Rare's Donkey Kong characters since the latter company were acquired by Microsoft in 2002, and thus now have full creative control on how they're presented and portrayed.

One detail that is worth pointing out, and may provide an explanation to why Nintendo had no qualms with redesigning a character who was meant to be Dixie's younger sibling into a teenager, is that the Japanese localization of Donkey Kong 64 reportedly makes zero mention of Tiny being related to Dixie, instead just being described by the manuals as just a "Charming girl Kong". It's also worth pointing out that every game that has featured Tiny Kong since 2002, such as Mario Super Sluggers, Super Smash Bros. Brawl, and Super Smash Bros. for Wii U has also made zero mention of Tiny's relationship with Dixie Kong, which adds credence to the theory that Nintendo opted to ignore and essentially retcon Rare's initial lore of the two being siblings.

In an interview with GamesRadar+, creative director George Andreas revealed that the game's notoriously high volume of collectibles was the result of an executive request from Rare co-founder Tim Stamper. According to Andreas, Stamper believed that the emphasis on collectables would help differentiate the game from Banjo-Kazooie, which the Stamper brothers had previously produced. This desire also influenced the decision to feature five playable characters and the inclusion of "thrilling moments" such as mine cart and slide segments.

The Gloomy Galleon level music in Donkey Kong 64 originates from Dream: Land of Giants, the game that eventually became Banjo-Kazooie. Fittingly enough, it was originally intended to be the theme for Captain Blackeye, Dream's villainous pirate antagonist, who would later go on to cameo as a non-playable character in Banjo-Tooie's Jolly Roger's Lagoon world.

As a bonus feature for Rare Replay, Rare included a set of music tracks dubbed "Top-Secret Tunes", which primarily features previously unreleased music from Rare games in development, including many hailing from Dream. One of these is a rendition of Blackeye's theme, called "High Tides, Swift Sails". While Rare had made efforts to avoid any legal issues with Nintendo as they were putting together Rare Replay (such as removing the remix of the Donkey Kong Land boss battle from its version of Blast Corps), this song's appearance may be an exception as the original version comes from a game owned by Rare that was never completed, while the game the song was repurposed for was never planned to be included in Rare Replay to begin with.

Donkey Kong 64 features a unnamed bat enemy found within certain stages such as Fungi Forest, Creepy Castle and Crystal Caves. This enemy would reappear in future games such as DK: King of Swing but under a seemingly new name: Flipflap.

It turns out that this particular name was already used for this enemy back in the Japanese localization of Donkey Kong 64. In the bestiary within the official Japanese DK64 guidebook, they are named フリップフラップ (Furippufurappu), which of course translates to Flipflap in English.

The infamous DK Rap was featured in the 2023 film "The Super Mario Bros. Movie", with the chorus portion used to chant Donkey Kong's name as he enters the Great Ring of Kong to battle Mario. Donkey Kong's voice actor Seth Rogen reacted to the DK Rap prior to the film's release, referring to it as "objectively one of the worst rap songs of all time." The original songwriter Grant Kirkhope expressed excitement upon hearing about the song's inclusion in the film, but was dismayed upon seeing that he was not credited as the song's original composer in the movie's credits.

Despite becoming a Microsoft game following the buyout of Rare, the ZX Spectrum version of Jetpac was left intact in the Wii U Virtual Console version of Donkey Kong 64.

Prior to the start of 2017, there were 976 known Banana Coins in the game. In early January of that year, a speedrunner discovered a widely undocumented 5-Banana Coin hidden in Fungi Forest while looking at how the game formats its save data. While looking through the stage's flags in the BizHawk emulator, the speedrunner noticed that the flag for 5-Banana Coins was incomplete, and used script analysis tools to reveal a DK Dirt Pile hidden under tall grass located near the Tag Barrel by the exit to the Chunky Minecart. Walking over the pile would cause the player to slightly bob upwards from the grass in an easy-to-miss moment, and slamming it revealed the 5-Banana Coin, bringing the known total to 977 Banana Coins.

The DK Rap uses samples from the Roland M-DC1 Sound Expansion Module.

There was a special edition Donkey Kong 64 controller released through Nintendo Power. Original advertisements showed the controller with the entire Donkey Kong 64 logo, but this was changed to only saying "DK64" by release.

If the player hacks their way back to Troff 'N' Scoff's room in a level where they have defeated the boss, the door will show a large "DK" with a green check-mark over it. It's possible this is a leftover of an unused way to go back to a room after a boss fight had been completed.

It's possible to access a test room without the use a cheat device. To do this, the player must have all of Snide's HQ blueprints, then bring up any level in the Bonus menu, highlight any of the mini-games, then press and hold B, and quickly press A. If done correctly, the player will be taken into the test room itself. The room has no music, three pedestals, a yellow balloon, and a motionless clone of Donkey Kong. It's not possible to leave the room, as pressing Start does nothing and going off-screen will take that player back to the room.

Early versions of the left and right trigger button icons can be found inside the game's code. These icons are much narrower than in the final game. They were mostly like widened to match the actual buttons on the controller.

An infinite life GameShark code increase the player's life melon count to 4, though the most you can have normally is 3. Even after disabling the code, your melon count will stay at 4. It's thought that Rare planned to implement an additional melon upgrade at Candy's shop. Alternatively, it's also possible that two melons were planned to be used at the beginning of the game instead of one.

A ROM was ripped from a demo kiosk version of the game, and was found to have three demo levels in it. They were the Army Dillo level, the Mine Cart level, and the Dogadon fight. Certain beta elements were in the ROM such as the silver balloon counter, Army Dillo's speech, and Dogadon's beta spit noise.

Using a glitch to get under DK Isle, going towards the waterfall will bring you to the escape ship cockpit King K. Rool used during the "K. Rool Press Button" cutscene.

It was originally believed that the only reason the game needed the Expansion Pak to run was because it fixed a game-breaking bug that caused the 4 megabyte game cartridge to randomly crash. Rare couldn't find any other solution, so they bundled the Expansion Pak with the game, costing them a lot of money. They still don't know what caused the bug. According to software engineer Chris Marlow:


However, developer Mark Stevenson claimed that while there was a game-breaking bug, it only affected one hardware revision of the Nintendo 64 that would be resolved on later models. He claims that the actual reason the Expansion Pak was required was because Rare's management instructed the game's developers to support it early in development to accommodate advanced graphical effects like dynamic lighting. Stevenson speculated that these two stories were likely conflated into one, creating the memory leak rumor that persisted for years.

Ultimately, Simon Craddick, one of the four engineers who worked on the Expansion Pak's implementation into Donkey Kong 64, claimed in a Facebook group that the only thing the Expansion Pak actually did was add vertex lighting to the levels.

ASCII text for ICE KEY is present in the ROM. The Ice Key is one of the Stop 'n' Swop items in Banjo-Kazooie, so there may have been intended to be a connection between the two games.

Early screenshots of Donkey Kong 64 showed that Donkey Kong's Treehouse originally had a shower stall in it with a poster of Banjo and Kazooie on it.

Grant Kirkhope, composer for the game, provided the voice of Donkey Kong.