Other mistake: The film is about a gang of Confederate soldiers after the Civil War, so a black man in the gang would seem a bit out of place.
Other mistake: When the Earp Brothers first arrive at Tombstone Fred White is telling them about the Cowboys and says "there's three of them now," the camera then shows four people wearing the red sash of the Cowboys.
Other mistake: Before the opening scene, where there is a paragraph setting up the history of the musical, in the third line there is a spelling error: "it's" should be "its" since it is a possessive pronoun and not a contraction.