Factual error: When Wyatt (Kevin Costner) becomes the sheriff/deputy/policeman of Wichita, Kansas, you can plainly see mountains in the background - there aren't any around there.
Factual error: In the opening shot of the film, a big oak door opens - carved in it is the date 1862 - 42 years after George III died.
Factual error: There is a theater showing 'La Dolce Vita.' That movie came out in 1960, but this film takes place in 1957 or 58 (since there is a reference to new 1958 model car).