Visible crew/equipment: In the opening murder scene watch when the man is stood outside the connecting train car doors, there is a shot from behind, moving in on him, and if you look out of the left window you can see a set of yellow ladders. This is set equipment and the train obviously can't be moving. (00:02:20)
Continuity mistake: During the sex scene between Milo Ventimiglia and Lauren Lee Smith, in which the fat guy was found dead, three consecutive shots showed that Milo Ventimiglia has his shirt on on the first, then the shirt disappeared on the next, only to reappear on Milo Ventimiglia's body again in the third shot.
Plot hole: At the end of the movie we discover that the main character (Claire) was in the plane crash and was sitting next to Eric as the plane started to go down. However at the beginning of the movie( before we are supposed to know Claire was in the crash) Eric can be seen but Claire is not next to him. (00:01:10 - 01:19:20)
Continuity mistake: At the end, Casey and Elaine flee the house in the Volvo and find Chloe's crashed SUV. As Casey goes to investigate the SUV on foot, Miranda suddenly comes sprinting out of the woods, intending to kill Casey. To save Casey, Elaine rams Miranda with the Volvo, slamming her into the rear of the SUV. A camera shot from inside the SUV looking out shows that Miranda impacted right in the center of the SUV's rear hatch. In the same shot, we see Miranda's lifeless body slowly slide straight down the hatch, meaning her body should have collapsed directly between the Volvo and the SUV. When the camera cuts to an exterior view, we see Miranda's lifeless body stretched out in the snow (parallel to both vehicles) a couple of feet away from the Volvo's front right fender; so her body is now about 6 feet away from where it should be.
Factual error: During the opening credits. An LCD screen is shown with lat/long coordinates. The movie takes place in the Persian Gulf. The coordinates are in the vicinity of Oceanside, CA.
Continuity mistake: When the first guy out of the main 3 is dragged to the hunting range (after having his spine exposed and meat cut off), he falls backwards into the snow and when he sort of rolls over, there is snow all over his exposed backbone and flesh but when he stumbles and gets up, there is no evidence of snow whatsoever.
Continuity mistake: Gina's father opens the door, club in his hand, and finds his family inside for the surprise party. In the reverse shot, Gina's position is also mirrored, having the right arm raised instead of her left. (00:08:15)
Other mistake: Jon's vehicle does not have the front license plate that is required in California. (00:57:23)