When Ashton Kutcher first read the script for the film, he almost turned down the role of Jesse because he found it to be "very stupid." However, when he read the "you got a tattoo" scene, he could not stop laughing and agreed to take on the part.
(at around 1h) Mark asks Jesse and Chester to email him via his website www.freakincage.com. The web address led to a photo of Mark in his cage. As of 2018, the link is now dead.
(at around 7 mins) The "Dude, where's your car?"/"Where's my car, dude?" dialogue is taken from a scene in The Big Lebowski (1998) that occurs between John Goodman and Jeff Bridges after they leave the bowling alley.
The film's story came from a rejected live action Beavis and Butt-Head (1993) movie concept in the late-'90s.
A sequel titled "Seriously Dude, Where's My Car?" was planned but was never developed and eventually the idea was scrapped.