Continuity mistake: The morning after the party at Steven's, Chip is at Steven's house making eggs for them, watch closely as Chip eats. While they are talking about Heather being a prostitute, Chip repeatedly loses the eggs off his fork, but continues to put the fork in his mouth, and makes a sound like he is actually eating the eggs. He does it about 4 or 5 times during their whole conversation.
Continuity mistake: In the scene at Steven's parents' house as Steven is yelling at Chip for being a felon, Chip gets up and slowly walks right next to Steven and whispers something in his ear, Steven instantly is moved back one or two feet in the next camera shot before he had a chance to move and he punches Chip in the mouth.
Continuity mistake: In the scene when the two guys (Steven and Ernie Douglas - the cable man) are sitting in the cable TV van, when Steven first asks about the cable guy's name, in the first shot we can see Ernie saying his name. In the next shot, he's making a strange smile and then the last shot shows a similar view to the first shot. It is clear that the first and the last shots were one complete and the smile in the middle was added later. There are two different head positions for Jim Carrey.
Continuity mistake: There are numerous instances in the film where Jim Carrey forgets that his character has a lisp. The most obvious example is when Chip goes to Robin's apartment to install free cable. In order to get Robin's attention he says "Apparently you have a secret admirer" absolutely flawlessly.
Continuity mistake: At Stevens parents house, Steven tells Chip Douglas to stay out of his life. Chip says, maybe I should just go, just then Robin stands up on Chip Douglas' right side and takes two steps in front of him and tells Steven he's an @-hole. The camera cuts to Steven and he says "what". Then when the camera cuts back, Robin is way behind Chip Douglas to his left.
Continuity mistake: When the cable guy (Jim Carrey) gets done drilling in the wall he says, "Suit yourself, no sweat off my sack." and Steven (Mathew Broderick) is seen in the background walking completely through the doorway. However, when the cable guy turns around and says, "By the way, you might wanna put on a bathing suit..." Steven is not even at the doorway yet.
Continuity mistake: At the end of the basketball scene, the camera is behind Chip and he is talking to Steven. He is standing in the center of the shattered glass from the backboard. When Steven walks away, the angle changes and shows Chip standing with all of the glass behind him, even though he hasn't taken any steps.
Continuity mistake: In the scene at Steven's parent's house, Chip is blackmailing Steven with the polaroid he took. When Chip shows Steven the picture, he says "bastard", and puts his hand over his mouth. In the very next shot, not half a second later, his hand isn't anywhere near his mouth.