Cheyenne Autumn (1964)

Factual error: The movie takes place in 1878. The Indians are all armed with Winchester repeating rifles. Indians of the period were more likely to be armed with old obsolete rifles (Civil War vintage) including some muzzle loaders with prehaps a sprinkling of Winchesters. Also, Indians were very proud of their rifles and usually decorated them with items such as brass tacks; no such decorations are to be seen.

Wyatt Earp: Say, you're the doctor around here. How come I always have to perform all the complicated operations?
Doc Holliday: You know I am a dentist, not a doctor. Wait until somebody shoot him in the teeth.