When the girl is shown being held in the air by the drill, on the ceiling of the sanatorium a modern age security camera can be seen despite the fact that the hospital was abandoned in 1974.
Charlie's face color changes between shots while having his nose bitten off.
Vincent's hair changes color and length while having a spike through his head.
Bloodmarks on snow after the last two death events.
At the beginning of the movie, when the cannibals escape and guard comes to check what's going on, he never locks em from a different angle.
One of the characters is mistaken about the vintage of a bottle of scotch abandoned 30 years ago. Spirits such as scotch ages in an oak barrel. When it's bottled this old aging process stops. So the 35 year old scotch he found is still 5 year old scotch.
Toward the end of the movie. As a car drives by, the camera pans to Lauren's frozen lifeless body sitting against a tree, Her eyes are clearly blinking.
When their are doing the fondue, a crew member can be seen walking in the back.