Revealing mistake: In the scene in which Jason kills the captain of the boat, it is quite obvious that Jason uses the blunt side of the machete to slit the captain's throat. (00:39:10)
Revealing mistake: When Jason kills the boat captain he comes up way short of making contact with the captain's throat. He's probably a good 2 inches away from it. It definitely doesn't help that this scene is in slow motion either. (00:39:10)
Revealing mistake: As Jason brings his arm back to punch Julius, the back of his neck obviously buckles like a rubber mask. (01:09:40)
Revealing mistake: In the scene when the crazy guy is hit in the back with the axe, when he falls, the axe sways side to side a little bit, then stops a couple inches of center from before.
Revealing mistake: Obvious dummies are in the car's back seats just before it slams into the wall. (01:12:35)
Revealing mistake: When Jason breaks his hand through the door it's really strange how his hand makes a perfect square on the broken door. Telling that the door was already broken and then repaired loosely for the stunt.
Revealing mistake: When Sean and Rennie run through the two glass doors leading down into the New York subway system, you can see Jason's shadow on the wall as he stands off camera and waits for his cue to walk on screen and kick his way through the glass doors. (01:19:25)