Factual error: Charles and Robert manage to outrun a charging Alaskan brown bear over a course of several hundred meters, leading it into a trap. This is absurd. The absolute maximum running speed of a human being is about 27 kilometers an hour, and that is for an appropriately dressed, fit athlete over a very short course on flat ground. They are in a rock strewn stream and are wearing heavy winter clothes. An fit, healthy, active male Alaskan brown bear like the one chasing them could hit 45 kmh in that environment without popping a sweat and could keep that up for a kilometer or more. When enraged or charging prey - as this one was - they have been clocked at 56kmh. This is nothing to do with an adrenaline rush - that will not enable Charles or Robert to exceed their body's maximum running speed by 200%.
Factual error: After Bob and Charlie kill the bear, they are shown wearing clothing made from the bearskin. How did they cure the skin so fast? A raw hide would not work for garments. Tanning a bear hide of that size would take about a fortnight even if they did have the necessary chemicals and equipment, which they show no sign of having.