Continuity mistake: When Chris drives up to Edgar's house, his windshield is dirty but suddenly clean thereafter. (00:11:37 - 00:12:57)
Continuity mistake: When Wyatt is shot, the amount of blood on his shirt next to the collar increases, decreases and even disappears between shots.
Continuity mistake: When we first see Agent Holloway viewing the crime scene photos taped to the wall, he is facing camera looking at transparent pictures on a transparent wall (as if we are behind that wall, seeing through it). When the angle changes to see the Agent from behind, the photos are now paper photos on a normal, opaque wall and the pictures are arranged somewhat differently - most notably to Holloway's right near the top where two wider photos are vertically aligned atop and below each other in the second shot when they were misaligned in the first shot by nearly half their width. The transparency versus opaque materials issue is a stylistic choice of the director and not a mistake, but the mismatched alignments is a mistake. (00:11:25)
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: When Will's mum takes her shoes off she is not wearing stockings. Will starts giving her a foot rub with nothing on her feet. When he goes to get the computer left by the neighbour his mum has stockings on. (00:15:20)