Other mistake: When Jason slices Pete's throat from the back seat with the machete, it goes deep, and blood should be gushing from Pete's jugular. But in the following shot, the edge of the knife has barely grazed the rest of Pete's throat, leaving only a fake trail of dried blood.
Continuity mistake: We see Vic outside the halfway house, just starting to chop a 4-foot log with a double-bit axe. In the same scene a few moments later, as Joey approaches, Vic has chopped about a third of the way through the log. Problem is, it's a completely different log (different shape, texture and color).
Other mistake: After Raymond gets stabbed by Roy and falls dead, there is no blood visible on his body.
Revealing mistake: During several of the deaths committed by the impostor, look closely. The shirt sleeves are dark green instead of the dark blue sleeves of the jumpsuit the impostor wears. Clearly Tom Morga, the hallucination of Jason, did these scenes instead of Dick Wieand, Roy Burns/impostor Jason.
Continuity mistake: The handle of the machete Jason stabs both grave digger guys with changes between shots. As he stabs the 1st guy, the handle is tripoint, but as he stabs the 2nd guy through the neck then pulls back, the handle now has a rounded end like a wooden peg.
Continuity mistake: As Tommy reaches Jason's grave, he hears laughter and voices coming from the woods. As the voices move closer we see lights in the clearing. Tommy runs off in the bushes to hide. Moments later, two guys with flashlights and shovels suddenly rush in, from the opposite left, instead of the clearing path at the right, from where they were.
Continuity mistake: While Eddie is being killed, in the second shot, there's a blood driblet on his bottom lip. In the next shot, his bottom lip is clean without any blood residue.
Continuity mistake: When Lana is hit by the axe, it hits her horizontally, but in the shot of her corpse, it is shown vertically.
Other mistake: After noticing that Tina is dead, Eddie fearfully backs away and leans against the tree. You can see Roy put the leather up and over the tree. This is impossible. He would have to whip it around the tree, not over it.
Other mistake: It seems unlikely that the police would have let Tommy keep Roy's hockey mask, as it's evidence.
Suggested correction: Already listed and corrected. It is possible that it was actually Tommy's dream.