Near the beginning of the film, Carmen and some others are standing in front of the High School, and Carmen lights up a cigarette twice between shots.
Two of the kids split off on their own and try out the water slide. After the first run down they both go completely under water. The girl then gets out of the pool and goes back up for another run down the slide. As she is shown starting down the slide, her long hair is now completely dry.
The condition and fractures in the glass that Greg tries to break in the restaurant keeps changing.
Martin is in the ventilation ducts and is trying to slide past the machete. It is along his leg several inches above the bottom of his shorts when the machete is pulled back slicing his leg. However, in the closeup it cuts just above the knee on bare skin, but in the wider shot the machete is still up on his shorts.