Continuity mistake: At the end of the movie, when Tim walks through the double doors, there is a toilet in the background which wasn't there in the previous scene. There was a table in its place earlier.
Continuity mistake: The beginning of Phantasm III starts with a flashback from Phantasm II. The car being driven in the flashback is a 1971 Plymouth Hemi 'Cuda, with four headlights, two distinctly separate hood scoops, and a hardtop. In Phantasm III, the car is a 1970 Hemi 'Cuda, with two headlights, a single Shaker hood scoop with dual openings, a "Hemi" stripe, and a convertible. It's supposed to be the same car, and in the flashback sequence it's easy to see the differences.