Continuity mistake: At the beginning, Eastwood dismounts from his horse to rescue the calf lying in the river. His horse is left standing in the river with the water up to his knees. When Eastwood places the calf on dry land, his horse is standing nearby. The horse's legs are dry.
Continuity mistake: At the end of the movie when Cheyenne is shaving, while Harmonica and Frank are having their shoot-out, he cuts himself at the sound of the gunshots. When Jill tells him that he is a handsome man the cut is gone. (02:22:25)
Revealing mistake: When Buck and the gang ride away from the saloon in Dallas where JC made a few new 'friends', the footage is sped-up for a second just as soon as James Caan jumps on his horse. (00:05:50)
Continuity mistake: Joe Bass, freshly robbed by the Indians, is asking the slave "You come a long way from home, you ran away?" In his hand is a bottle of liquor with the cork on. Change shot, the bottle is open. New change, and now the bottle is closed again. (00:08:00)
Revealing mistake: When Loco is tying up the hands of one of his dead bounties (as the stagecoach with Sheriff and Silence turns up to collect them) you can see the breath of the other "dead" man in the cold air. (00:28:38)