Factual error: When Billy The Kid is taking a bath and dictating a letter to Doc, intended for the governor, he says he is in the Mexican village of Juarez. This town was actually named "Paso del Norte" at the time, it wasn't until 10 years after the events depicted in the film that it was renamed "Ciudad Juarez."
Visible crew/equipment: When Buckshot Roberts is going into the outhouse there is a sequence of shots that show Billy the Kid, Dick Brewer and Dirty Steve hiding behind a pile of logs. In almost every shot where these three are seen behind the logs you can see a camera tri-pod leaning against a fence. The sequence lasts over a minute so you have several chances to plainly see it.