Revealing mistake: In the final shootout scene, when Rambo takes over the truck mounted machine gun, he shoots the driver, whose blood splatters a lot over the metal guards on the gun. If the blood splattered that much on the guards, it should be all over the interior of the truck which is revealed to only have blood on the floor - none all over the dash or doors.
Revealing mistake: At the end of the finale battle when the the films villain gets sliced open by Rambo, the effect shot of him rolling down the hill after Rambo kicks him is laughably fake. The injury sustained to him required the villain's upper torso to move almost completely disjointed from his lower torso. The computer-aided effects are sub par, the blood splatter is misplaced on the actor's body and the movements are impossible. Not to mention the fact that Rambo obviously could not have cut through his spinal cord, which would have made it impossible for the body to move in its disjointed manner.