Continuity mistake: In the scene were Tina asks Michael to stop the car at the store he starts driving faster going at least 30mph for 7 seconds. When he finally stops and backs up he drives about 5-10mph and ends up outside the store in 4 seconds.
Continuity mistake: When Michael rams the pitchfork through Spitz, it is at the lower end of his back, nearer to his waist even. A few seconds later when Spitz's girlfriend comes at Michael with the same pitchfork, some other shots of the now dead Spitz show the pitchfork holes up near his shoulder blades, probably 6-8 inches higher than where they should be.
Continuity mistake: The mask Michael wears when he comes out of the mineshaft is not the one he was wearing when he entered, the lips are different.