Continuity mistake: When Paul goes to get pizza and a movie for Dora, the movie messes up the order that he gets them. First, he goes to the pizza place, and picks up a pizza, you can clearly see him holding a bag. Then, he goes to the video store (with a cameo by David Spade), he has nothing in his hands. Then, he has both after.
Continuity mistake: When Paul discovers the waterbed leaking, he wakes his roomates up and they both hold the bed up. Paul is wearing a brown T-shirt. You see Paul holding the bed on the right and the other guy on the left. The shot changes to the other 2 guys coming in the room behind them and you see Paul's brown T-shirt on the right of the screen when it should now be on the left. It shows Paul and his roomate again and they have swapped places.
Continuity mistake: When Chris and Paul are talking in the dorm room after Chris has finished dancing to "Pretty Fly (for a white guy)" and he pulls up a chair. Throughout the whole conversation all the shots behind chris show his hands crossed, but all the frontal shots show his hands down in front of him
Continuity mistake: When you see a street shot, they show Studio 54 next to the Imperial Theatre. The mistake is a huge one - Sudio 54 is on 54th Street and the Imperial Theatre is on 45th Street.
Continuity mistake: Paul and Dora try to give the weakened kitten to the mama cat, the mama cat switches sides through the whole scene. She goes from being closer to Dora(right side) to closer to Paul(left side)from shot to shot.