Fred McDougall was a longtime extra on the series. Here he has a bigger role than usual as Trooper Kelly and even gets to say a line: ''He ain't in here Sergeant''.
Must have run short on 'extras'. Near the end of the story, the soldier dismounts and heads into the saloon. The couple that are seen walking by are very likely Doc & Kitty. Most certainly Doc as he is wearing the same hat and clothes, possibly Kitty as well but not as certain.