When the two protagonists first enter the Alaskan lodge, there is a large mounted deer head visible on the wall immediately inside the door on one side of the window. Later, when the bad guys ambush them, the deer head has moved to the wall on the other side of the window.
When Col. Marikoff fires his machine gun at Mike (who has a hold of Muller in front of him, with a knife to his throat) Muller is killed but Mike is unharmed, who surely would have been either killed or wounded by the bullets passing through Muller.
When Mike flies to Twin Lakes, the flight takes 6 minutes of film time, and so the distance must be several miles. And yet when the group walks through the tunnel, they appear to get there in only a few minutes.