Other mistake: When Bonham starts his search for Hallam in the forest we see him crawling along with his face and shirt nice and clean. From one shot to the next his face is covered with movie dirt, and his shirt looks as if he hadn't changed it in at least a year. Fresh dirt looks different.
Other mistake: On the final hunt, both Bonham and Hallam sit down and produce knives in a very diligent manner, Bonham from a flintstone, and Hallam from a piece of scrap metal in a complete forging procedure. Given the time pressure both opponents are under, this display of stone- resp. iron-age skills (a.k.a. survival skills) is a bit absurd and almost touching.