Continuity mistake: When the snooty English economics professor first spots Thornton and his son in his class, we can see two empty seats directly in front of them. However, when the camera moves to the back of the room, the two chairs are filled. This happens a couple of times during the scene as the camera angle changes.
Continuity mistake: During the fight scene in the bar, after the pep-rally, Lou (Burt Young) is seen pressing a guy over his head. The guy is wearing a denim vest, with a red sweater on underneath. After Lou throws the guy's head into the jukebox, the guy who is sticking out of the jukebox is wearing a full denim jacket. The red sweater and vest disappear.