Other mistake: During the credits, in the shot of the diner, the asian man sitting to the right glances right at the camera. (00:02:00)
Continuity mistake: When the boat is sailing along, it reaches the 'Camp Crystal Lake' sign. When Jim throws the anchor over, it should have sailed well past it, but it has actually gone backwards. (00:03:05)
Continuity mistake: By the radio on Jim's boat is a bottle with a boat in it and the cork in the bottle is pointing to the left side. When Suzi gets up to check on the noise, the bottle is visible and the cork is now pointing to the right side. (00:03:45 - 00:07:30)
Audio problem: When Jim says "Gotta throw the anchor over" his mouth is slow and out of sync. (00:04:25)
Other mistake: When Jason is resurrected in the lake, the water is quite well lit, even though it's night and there aren't any real light sources to light the lake up. (00:06:00)
Continuity mistake: When we see Jason lying on the bottom of the lake, we also see some chains lying around. At first we see the upper chain lying out on the edge of a plank. But when Jason gets electricity through him we see the chain has moved in to the middle of the plank. (00:06:15)
Continuity mistake: There is a large blue cooler by the stairs in the boat, under two postcards. But in the shot where Jason clips the harpoon, before shooting it, we can see the cooler has vanished. (00:07:40 - 00:09:00)
Continuity mistake: The arrow that Jason shoots at Suzi which hits the wall beside her changes angle when he rips it out of the wall. (00:09:20)
Continuity mistake: After Jim is stabbed, he smears blood over a window. Later when we see the boat drifting towards the harbour, we see the window and the smears of blood are now much different. (00:09:40 - 00:12:30)
Continuity mistake: When Sean is given the present by his father, there is a polystyrene pad next to the computer navigator, which is sticking out. In the next shot it's pushed in neatly. (00:14:25)
Revealing mistake: Throughout the movie, the black cloth covering Jason's eyes under the hockey mask is really noticeable, especially when he grabs onto the rope to climb aboard the Lazarus. (00:15:25)
Continuity mistake: In the film Sean and Rennie are on board the Lazarus. Sean puts both of his hands into his jacket pocket to get Rennie's gift. He never hands it to her, but In the next shot she has it in her hands. (00:16:55)
Continuity mistake: When Rennie gets the present from Sean, she opens it twice in two shots. (00:17:00)
Continuity mistake: When Wayne is taping J.J., between shots his left hand moves from down by his side, to on the focus of his camera. (00:18:20)
Continuity mistake: The position of the black glove on J.J.'s left hand changes between shots as she switches off the tape while playing her guitar up on the deck. (00:18:25)
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)
Audio problem: When J.J. is jammin' to her song she notices Jason and screams. She then runs away, and magically the song that was playing on her tape player has stopped. (00:21:15)
Factual error: When J.J. sees Jason she drops her guitar running away. The guitar then feedbacks. But when J.J. confronts Jason again he has the guitar with him, unplugged, but still we hear the sound of feedback. (00:21:25)
Revealing mistake: During the part where J.J. goes down to the boiler room to play her guitar, Jason sneaks up behind her. She screams and runs down more stairs, and then right before Jason kills her, as he lifts the guitar to hit her, in the lower right hand of the screen you can see the blood coming out of the guitar before it hits her. (00:21:25)
Chosen answer: To the best of my knowledge, this is just a bit of a continuity mistake. While previous films have not indicated Crystal Lake is connected to the ocean, this film portrays it as being connected. You just kinda gotta go with it for the movie to work.
TedStixon