Revealing mistake: In the scene when Rusty hits Chip with the lamp near the end of the movie, you can see the lamp miss his face.
Revealing mistake: After Chip is hit on the head with the lamp and calls the police, they appear to arrive only a matter of seconds after the call, and begin to chase Rusty and Willard right as they are exiting the house.
Factual error: After the attempted kidnapping, Norm Macdonald's face is in the Newspaper the next morning. This is not possible because the crime was committed the night before and not discovered until the very morning his face is in the Paper. There would not be enough time for that article to be written.