The Black Dakotas
During the fight between Brock Marsh (posing as Zachary Paige) and Sioux Indian Spotted Deer, the flaming torch used as a weapon by Spotted Deer goes out at one point and then is seen burning again.
The firearms used throughout the movie post-date the American Civil War. These include Colt Single-Action Army revolvers (a.k.a. Peacemakers) and various Winchester lever-action rifles.
During the last confrontation at the stagecoach, Ruth Lawrence is wearing a modern bra.
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