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.
An interview with Chris Sevor 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 kids 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.
One of the developers 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.