Plot hole: Where exactly did all the other people go on the ship? In the beginning of the movie there were people everywhere then all of a sudden it's down to the main characters.
Plot hole: How did Jason get the boat from Crystal lake to the open ocean?
Continuity mistake: After Tamara comes out of the the shower she is completely dry. (00:36:00)
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: As Sean dives into the water to save Rennie, in all the overhead shots Rennie has dry, curly hair, but in closeups her hair is soaked down straight. In the overhead shots it's obviously a stunt double. (00:30:10)
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)
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)
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)
Revealing mistake: When Jason strangles Eva, you can see where the rotten flesh makeup ends on his arm, and that the rest is just a fabric sleeve. (00:46:10)
Visible crew/equipment: When Tamara pushes Rennie, as Rennie starts to fall you can see a crewmembers hands reach out to catch her. Look close and you can even see the red tee-shirt sleeve of the person. (00:29:20)
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)
Visible crew/equipment: As Jason is walking down some steps, a little after he kills J.J., you can see the shadow of a crewmember pushing equipment, cast on the wall. (00:21:55)
Continuity mistake: When Jason grabs the man in the diner he is several paces to the right of the mirror, but when he throws the man into the mirror Jason can clearly be seen in the reflection standing right across from it. (01:24:35)
Visible crew/equipment: When the boxing scene starts, as the camera pans past the punchbag, the shadow of the camera is clearly cast on it. Then as the camera continues to pan past the punchbag, you can see the sides of two crewmembers come into view (who are following the path of the camera.) They are both wearing a jumper and jeans. (00:23:05)
Continuity mistake: In the scene where Tamara gets out of the shower, her silk gown which hangs on the handrail changes position between shots. (00:35:45)
Visible crew/equipment: When Eva is in the disco, after Jason bursts in, as she pulls at the second locked door, you can see the reflection of two crewmember's faces in the silver disco pole. (00:45:30)
Continuity mistake: The shards of glass around the porthole change between shots, as Jason attacks Rennie. (00:53:40)
Visible crew/equipment: When Rennie is searching for Toby, the camera then pans to the games room, and reflected in the four pictures hanging up on the wall is a crewmember giving Jason a signal to come on cue. (00:26:00)
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