When the game was still new and popular, rumors persisted that Luigi and Wario were in the game. These rumors have long been proven false, although those characters did appear in the later port, Super Mario 64 DS (2004). But in 2020, deep in the code someone found Luigi. He is not used or accessible in the game, but he exists in the code.
The sound for the Boo's cackle was the sound effect used for Bowser's laugh sped up. When the sound is played at normal speed it's a group of people laughing.
Usually when you get the eight red coins in a level, the camera switches to show you where the star has appeared. But due to a glitch in the game, this does not happen in Big Boo's Haunt.
With sales of 11 million units it was the best selling Nintendo 64 game and the best selling 5th generation console game.
Was voted as the most important video game ever by Electronic Gaming Magazine (Jan 2005).