Ben Johnson appears uncredited as a member of Marshal Hampton's posse. He even has a line or two of dialogue. He and the marshal and another deputy dismount and enter a building on location. In the next shot, the studio interior, Hampton and the deputy come through the door, but not Ben.
Lawrence Tierney played famous outlaw Jesse James. A few years earlier he got his break as another iconic outlaw in "Dillinger".
Although the badmen of the film are actual persons, the character of Chief Tahlequah is not. Tahlequah is a city in eastern Oklahoma, the capital of the Cherokee Nation, but the word itself is derived from a type of grain grown in the region, not from a person.