Continuity mistake: When the boxer is boxing with Jason, you see that his hands get cut up and are bleeding heavily during the fight. He continues punching Jason in the mask, but never leaves a drop of blood on it. (01:09:20)
Factual error: When the captain gets his throat slashed, hardly any blood comes out. When a persons throat is cut, blood will pour out in large volumes as there is a major artery in the neck. (00:41:00)
Continuity mistake: When Jason is walking down the stairs toward J.J. his left foot comes off the last step but in the next shot it's his right. (00:20:55)
Continuity mistake: The black sludge on the girl's white pants when she's in the sewer at the end is constantly changing. It sometimes changes position or isn't there at all in later shots. The best example is when she lures Jason away from the guy that just got knocked out and runs into the dead end. She slides down the wall next to the toxic chemical container and the back and sides of her pants are completely covered in the black sludge, when she runs away, her pants are totally clean. (01:27:55)
Factual error: When Rennie and Sean are on the ladder and the toxic waste is flooding through "destroying" Jason, they are completely unscathed. There is no way there would be no splash back burning them, plus the fumes from the toxic waste which they are subjected to would have done them serious bodily harm.
Factual error: Jason stabs the druggie with the needle and it comes out the front, but his hand is only on his back and the needle isn't long enough to go through to the other side. (01:08:35)
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)
Continuity mistake: In the police car Rennie jumps into the driver's seat and drives off, while the other three stay in the back. After the car crashes, Sean has suddenly moved to the passenger seat. (01:11:35)
Plot hole: Jason all of a sudden can drive a boat and out of nowhere, seems to know about a cruise ship filled with teenagers ready for him to kill. Yeah, makes sense to me. Especially since there is land with buildings right where Jim and Suzie drop anchor on their boat. Jason gives up killing people in those buildings to drive to a cruise ship that he cannot possibly know about? Also the fact that the survivors get to New York and minutes later Jason just happens to pop out of the water? Are we led to believe that he not only learned how to swim to New York but he managed to not kill everyone while they were in the life raft?