Continuity mistake: Towards the beginning of the film, as Jeremy Sisto walks down the road, he's wearing a flower necklace in the scene before his girlfriend has picked the flower for him. In the subsequent scene when she picks it, he's not wearing it.
Suggested correction: It's not the same flower, actually. She picked that one when he already had one on his necklace—it's just hidden in this scene.
Continuity mistake: When Chris is hiding under the bed with Eliza Dushku, after the mountain-men drops the corpse, we see blood flowing towards the left hand, that is under the Chris's chin. In the next shot, the hand is the right one and after that it is the left one again. (00:31:49)
Continuity mistake: When Rich and Hailey are rock climbing, Rich reaches the top and is then killed and blood drops onto Hailey's face. It is in droplets, then Hailey wipes it, so it smears across her face, then it changes to a droplets again, then to smears, and the location, shape and size of the drop/smears differs too. (00:02:10)
Visible crew/equipment: When Scott falls after getting hit by the three arrows, you can clearly see a long tube leading all the way up his leg which pumps the fake blood up to his shirt. (00:41:25)