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 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 Il grande 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.
There are Chinese characters on the sign for the Chinese drive-through restaurant where the woman on the speaker always says, "And then?" The characters, read "hai you ne" in Mandarin, can be translated, "Is there anything else?" Or, as she says, "And then?"