Did You Know? Donkey Kong 64

I'm starting a new series about facts about gaming called "Did You Know?". It's based off facts I know and facts from www.didyouknowgaming.com . So here it is:

The reason why Donkey Kong 64 needs the expansion pak to run perfectly is because DK64 will hit a game breaking bug without an expansion pak. Rare knew about the bug and saw the expansion fixed the bug. Rare threw the expansion pak in for free saving Rare a fortune.