Factual error: The events in the film take place in mid-1929, as evidenced by the first Academy Awards being presented in May. However, Wyatt Earp went to the happy hunting grounds in January of that year.
Factual error: The bad guys are vanquished, and Wyatt boards the train and heads off into the sunset. Two problems with that scenario: from Los Angeles, heading West puts you into the Pacific, and Wyatt didn't have to take the train, he lived on West 17th Street, in Los Angeles.