Acclaimed Flop: Though it received positive reviews and has become a Cult Classic, the game did not sell very well, due to Nintendo refusing to promote the game on top of its coming out at the very end of the Nintendo 64's life cycle when people were more focused on the already-released PlayStation 2 and the upcoming GameCube and Xbox.
Dancing Bear: Conker was a level of black and crude comedy normally seen in an episode of South Park and it was coming from Nintendo (albeit from what was then a second-party developer).
The main reason why Conker's Bad Fur Day was created was because the executives at Rare began to fear that their original idea for a Conker platformer, Twelve Tales: Conker 64/Conker's Quest, was going to be looked down upon due to being yet another cutesy platformer, and an extremely negative critique/mockery made during its test showing ended up being the last straw, ultimately resulting in this.
Microsoft made Rare censor the remake, despite the fact that it was an M-Rated game on a console targeted mostly at teenagers and young adults (and despite initial claims that it'd be uncensored, it was originally called Conker: Live and Uncut after all).
Averted with the Rare Replay port. The game is completely unaltered, apart from the new button prompts on the Xbox One (although Conker does originally refer to the original Nintendo 64 control scheme in the voice acting).
Keep Circulating the Tapes: The original N64 version was stuck in this for years. While the Xbox remake came out in 2005, and was easier to get a hold of, it's widely considered to be the inferior version. Fortunately, the original N64 version was put into Rare Replay with almost no changes. This had the side effect of switching positions with the Xbox remake, making that version the harder one to get.
Screwed by the Network: When Nintendo discovered Rare's provocative change in direction, they refused to acknowledge the game's existence in Nintendo Power (though not in their foreign associated magazines from Mexico or Brazil) and other media outlets, contributing heavily to the game's low sales.
An interview with Chris Seavor revealed that not only did they plan on making a sequel to Conker's Bad Fur Day, aptly named Conker's Other Bad Fur Day, but the plotline of the game was actually finalized. However, Microsoft decided against doing a sequel until they decide to ask, so development was shelved. The only known parts of the plot revealed to the public was in the beginning, where Conker was dethroned, imprisoned, and awaiting execution because he wasted the entire royal treasury on beer, parties, and hookers. He then has to make an escape from the castle's highest tower with a ball and chain attached to his leg.
The game was originally a more kid-friendly platformer in the vein of Banjo-Kazooie. At first it was Conker's Quest before changing into Twelve Tales. This younger version of Conker can be seen in Diddy Kong Racing, and the Game Boy Color game Pocket Tales; some Posters released for the remake of Bad Fur Day says both are canon and take place in the past. You can view 30 minutes of gameplay in this unreleased game here.
Chris Seavor mentioned that a cutscene mocking Pokémon was removed due to Nintendo's request. Amazingly, those who hacked the files of the beta version actually found said scene.
As seen in this video, there was originally a scene where two Tediz surgeons are experimenting on a squirrel soldier while he's still alive not unlike the Nazi experiments during the Holocaust. It was replaced with the Tediz Breaking the Fourth Wall by talking about the game before turning their attention to Conker.
According to Chris Seavor, the Xbox remake was going to have a gate character called "Bill Gate" who owned a house whose windows kept breaking. It seems Microsoft didn't appreciate the joke.
The music that plays during the Count Batula sequence was originally intended as the battle theme for an unused vampire character in Killer Instinct 2.