Continuity mistake: When John loses his voice, he uses a pad to communicate with Charlie. He writes "I need you to stand guard" in one scene and later shows the same message to Charlie. In the second scene, although it is supposed to be the same message, guard is misspelled "gaurd."
Continuity mistake: After picking up Eddy the hitchhiker, John and his passenger can be seen driving through a compound. As they drive through the compound, a passenger can be seen in John's pick-up truck. The scene just before they arrive at the sweat lodge, there is no passenger. Once they arrive at the sweat lodge, a passenger exits the pick-up truck.