Chris Seavor voiced all of the male characters in the game besides The Great Mighty Poo.

In the original game, if you stand idle for a while, Conker will get out his Game Boy and play it. You don't get to play with it, but you can hear him playing Killer Instinct, another game made by Rare. In the game's remake, the console is replaced by a handheld console resembling the Game Boy Advance SP, where he can again be heard playing Killer Instinct. This idle animation was disabled in the Rare Replay release of the original game in 2015.

Conker's Bad Fur Day started out as a much tamer game called Twelve Tales: Conker 64. Around the time of its announcement, Rare had already made two similar games, Banjo-Kazooie and Diddy Kong Racing. They feared criticism for making another innocent platformer starring "cutesy" animals, prompting them to completely redesign the game for older audiences in 1999. Rare kept it under wraps after this announcement, but assured it was still in development until the revamp was formally revealed in 2000.

On the charcter select screen (the bar), you can see Banjo's severed and stuffed head mounted above the fireplace and if you look in the closet you'll find Kazooie's stuffed head being used as an umbrella handle.

Originally there was a cutscene making fun of Pikachu in the game. After hackers discovered a Pikachu tail in the game's code, a fan asked the game's designer about it and he told the story in a tweet.

If you input curse words or insults into the cheat menu, the fire devil will hurl insults back at you.

The opening sequence of Conker's Bad Fur Day is a parody of the intro from the Stanley Kubrick film "A Clockwork Orange".

There was a sequel being developed called "Conker's Other Bad Day", however it was cancelled. The plot would've dealt with Conker's bad tenure as King after spending the treasury money on beer, parties and hookers. The game started with his escape, with a ball and chain attached to him, from the Castle's highest tower where he had been faced with the prospect of execution. According to Chris Seavor:

Development on "Twelve Tales: Conker 64" began around the same time as "Project Dream" (later "Banjo-Kazooie"), however work on the game was put on hold for a long time to focus on improving "Banjo-Kazooie" and other experiments.

The Great Mighty Poo's death dialogue is a parody of the Wicked Witch of the West's death dialogue from The Wizard Of Oz.

The word "Butt" is misspelled as "But" in the last verse of the lyrics displayed during The Great Mighty Poo's boss battle. This was corrected in its Xbox remake, Conker: Live and Reloaded.

At the main menu screen, the mounted head of Banjo and the Kazooie umbrella weren't just references to the characters from the Banjo-Kazooie series, but statements made by the developers about their rivalry between the development teams at Rare. The developers would see each other's work and become jealous over the progress that they'd seen.

Rare presented the scene where Conker urinates on the fire devils to Nintendo of America's founder Minoru Arakawa and its then president Howard Lincoln. Arakawa found the scene to be hilarious, but Lincoln didn't find it funny at all.

An ending considered for the game was to have all the characters hugging each other, a juxtaposition to the brutal violence seen throughout the game.

The developers wanted to have outtakes of cutscenes play at the end during the credits with scenes like Conker being bad-tempered on set or the characters being out of character, but it was left out due to time constraints. Later the developers regretted leaving it out after seeing the film Toy Story 2 do something similar.

After Conker cuts Franky the Pitchfork from the hanging rope, Franky says "It was like one of them executions you hear about." to which Conker glances over at Ron & Reg who appear as executioners. The scene was originally to have Franky say "It was like one of them lynchings you hear about." with then Ron & Reg dressed as Klu Klux Klan members, however Nintendo were shocked at the idea and decided against it.

In the scene where Birdy sells Conker the manual and the cash escapes Birdy's pocket, Conker was originally going to either pull the money back with string, or whistle for it to come back. However, the game's designer, Chris Seavor, didn't want him to be seen as a thief.

Birdy the scarecrow is based on Paul McCowell who was the units adminstrator at Rare.

Gregg the Grim Reaper was named after Gregg Mayles, one of the designers on the game.

According to composer Robin Beanland, the farts in the song "Poo" were inspired by the song "Uncle Fucker" from the film "South Park: Bigger, Longer & Uncut"