Continuity mistake: At the end of the movie, when Liam Neeson looks around at the wolves approaching from the forest, the black frostbite mark on Liam Neeson's face is on his right cheek instead of his left cheek. (01:50:00)
Factual error: The wolves in this movie must be some sort of mutant super wolf. North American Grey wolves are not lion sized killing machines. They are typically smaller, by weight, than an average German Shepherd.
Continuity mistake: Close to the river, while John is sitting because he is aware he is going to die, Ottway is wearing some light blue shoes. In the final scene, Ottway enters it with black shoes. Although they might have got wet, the shoes seem different.
Plot hole: How did the wolves get across the canyon? Unless they were flying wolves, there's no way they could.
Suggested correction: Just because we don't see how they got across doesn't make it a plot hole. We see next to nothing of the area surrounding the canyon. There could have been a pass or trail in the distance that the wolves used. The characters think they are gradually walking away from where the wolves' den is, so they decide to use a makeshift zipline to get to the other side rather than go back the way they came and risk running into the wolves again.
Factual error: The river that Ottway jumps into is filled with water from snow runoff, and as such it is barely above freezing temperature. Under those conditions, most people might have a few minutes to live before hypothermia and death. When Ottway gets out of the river, he isn't even shivering.
Suggested correction: This is a follow-up question for this entry and not a correction, but since we can't comment on entries, this is how I have to do it. Ottway has been in the freezing Alaskan wildness for at least a couple days at this point, so his body's core temperature would have gradually dropped in that time. With that in mind, is it possible he could have emerged from the river without being cold enough to shiver? Wikipedia even lists the symptoms of moderate hypothermia as "no shivering, increased confusion."
