Revealing mistake: When he rolls the allegedly dead guy over in the snow, (after he hit him with the crowbar), the body's breath is visible in the cold.
Revealing mistake: As Jacob is changing the tire, there is a hint of sunlight out as he and Hank are talking. As Hank returns from the plane, it's snowing and grey outside, as you see Jacob club Dwight. As Hank finishes killing Dwight, it's still snowing, but when Hank and Jacob discuss that he wasn't completely being dead, it's back to having sunlight and no snow falling.
Continuity mistake: Near the end of the movie after the fake FBI agent shoots the sheriff, there is a scene where you see the sheriff's dog lying next to him. When the dead sheriff is shown again a few minutes later there is no sign of the dog or even dog footsteps in the snow. (00:09:00)
