Revealing mistake: When Wayne has gone to the church for Cassandra and finds out that it is actually the one across the street, he walks across between them. If you look where the sun is coming from, his shadow is actually in the wrong direction when he is between them. (01:18:10)
Revealing mistake: When Garth is floating in the air kissing Honey Hornee you can see the black wire that's holding him up against the background of the white lampshade. (00:57:45)
Continuity mistake: During the beginning of Wayne's "fight" with Cassandra's father, a white Stratocaster guitar can be seen in the background, but the guitar disappears after the two switch positions.
Continuity mistake: When Wayne brings Del Preston to Stan Makita's, Del tells his M&M's story, and a waitress walks behind Del with tea, serves it, and walks away. The camera switches to Wayne and then back Del. The waitress is now behind Del even though she left before. (00:23:15)
Continuity mistake: At the start,Wayne re-introduces us to Cassandra in a dream sequence. She is shown playing bass left handed. In the first movie,she plays right handed.