Continuity mistake: When Jesse and Chester meet the outer space chicks for the first time one of them takes Jesse's Popsicle, swallows it and pulls the stick slowly out of her mouth. At this point it is still red like the Popsicle. We see Chester and Jesse look at her and in the next shot the chick pulls out the whole stick but now it is completely clean, no more red dye on it.
Continuity mistake: When the boys are taking the garbage out of their girlfriends' house, the bags they're carrying change size and colour from shot to shot.
Continuity mistake: At the ostrich place belonging to Pierre, they climb the perimeter wall and jump from the tree. As they jump, they are side by side and as they fall on the ground in the next shot, they are the other way round. They don't seem to swap sides as they fall however.
Continuity mistake: Right before they get picked up by the followers of Zoltan there's a little girl playing hopscotch who disappears and then reappears in the next clip.
Continuity mistake: When the main character orders fast food at the drive in, he first has his arm outside the car, then the camera angle changes, and the arm is inside, and so on...