The two boys, with whom Judy sits when Paul first gets Angela to talk to him in the rec hall, change between shots.
During the fight between the boys in the rec hall, the cowboy hat on the floor moves back and forth between shots.
At the very beginning, when the two kids sit on the boat, there's a huge gap between them in far shots, but in a closeup they sit right next to each other.
Angela gains a red bathing suit in the medium shot of her at the beach at the end (Media Video version only).
The waterskier in the introduction suddenly disappears, then reappears.
The cop at the end of the movie has an obviously fake mustache.
Before Judy gets killed, the killer standing in the doorway is obviously Jonathan Tiersten in a wig.
Obvious dummies are inside the speeding boat that runs over John.
When the boy is under the canoe, it is unusually light. It is night-time, so it should have been pitch black when he was under the canoe.
In rec hall fight, then same two girls in white shirts (one with a green collar and one with color stripes across chest) are in both shots - holding hands with boys when the older boys are seen, and chatting in a small group when Ricky is being restrained.
The tight yellow t-shirt that Paul DeAngelo wears, that reads "Universal Bodybuilding and Weightlifting," is misspelled. The word "bodybuilding" lacks the L and reads "bodybuiding."
A hornets' nest drops on a victim, whose face becomes covered with bees. Bees don't live in hornet nests, and the film dodges the point by never mentioning the words hornet or bee (or wasp).
When Eddie and the little kids go camping with their flashlights, the light reflection of the camera hits Eddie in the face.
At the end, when Angela is sitting and humming, a person is visible on the other side of the bleachers.
The mic rod shadow is clearly visible on the overturned boat when the family talks about Martha in the water.