Throughout much of the movie, Liam Neeson's character has a large bruise on his left cheek. I don't recall if this injury occurred in the plane crash or his first scuffle with a wolf, but it was fairly early on. 1 hour 46 minutes into the film, his character is kneeling down piling the wallets of the dead people. Wolves begin coming out of the woods & Liam is shown looking from side to side. At one point, the camera is to his right, and the bruise previously on his LEFT cheek is now suddenly on his RIGHT. A moment later, when the camera is on his left, the bruise is back on his left cheek.

Obviously, this was the result of a film flip, but should have been caught post-production.