When Ashton Kutcher, first read the script for the film, he almost turned down the role because he found it to be "very stupid." But when he read the "you got a tattoo!" scene, he could not stop laughing and agreed to take on the part.
When Mr. Pizzacoli walks into Jesse and Chester's house, out the window there is a driveway, but when they leave their house, there is no driveway. This also happens when the twins come over to break up with them.
When Jesse and Chester are taking out the trash in their girlfriends home, Jesse takes off one shoe and Chester takes off one shoe and sock but directly after when they drop the trash, you can see they both have their footwear back on, and in the next shot, when thrown outside their footwear is off again.