Factual error: Monument Valley is certainly not one mile outside of Dodge City Kansas as it appears to be in this film. In fact there are no mountains that tall anywhere near Dodge City Kansas, but they appear in this film.
Factual error: The narrator mentions that the Cheyenne tribe split in half in northern Nebraska. The scenery would suggest otherwise, as there are no mountains that high in Nebraska.
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.
Factual error: The warehouse scene when they were locked up. The lantern that lights their faces in the window is a Coleman lantern. That type of lantern was not made until about 1930's.
Factual error: The cattle drive scene features Polled Hereford cattle. Polled Hereford were not developed until 1895.