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.
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: 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)
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)