A Border Patrol Agent who was patrolling the U.S. Mexico Border on horseback came upon the remote set during filming. He was offered a part in the movie by Elizabeth Martin (who later became Mrs. Elizabeth Shatner). He plays a "Man in Black" Agent arresting a local citizen as the main characters enter town and later plays the cowboy character that fights Tom Towle's character in the movie's finale.
Bill Shatner rode horseback on the U.S./Mexico border with a Border Patrol Agent (who appears in the movie in two different roles) during the filming of the movie in Bisbee, Arizona. Shatner talked about that experience in an interview on both the Conan O'Brien Show in 2001 and later in his autobiography "Up Till Now" (published by Thomas Dunne Books) in 2008.