Continuity mistake: When Carl Weathers gets killed, he is on the ground with his left arm lying across his forehead. The camera cuts away to Lee Marvin who walks back from the edge of the cliff to Weathers, and in the next view of Weathers, Weathers' other arm - his right - is now across his forehead.
Continuity mistake: As the posse is attacking Johnson's cabin, one man runs up and kicks down the door. Johnson shoots him, then the door swings back and closes on its hinges again.
Factual error: The spotter pilot is Captain Tucker of the Royal Canadian Air Force. But the RCAF of the 1930s used RAF ranks. He would actually be a Flight Lieutenant.