During the final gunfight, when one of the outlaws is wounded, he falls against a "boulder" that moves.
Hollister is shown riding up to Curly Bill's saloon. The camera changes to inside the saloon as Hollister comes inside and the only thing seen outside the doors is gray nothingness. This scene was probably shot in the studio and perhaps the producers didn't want to bother with having an outdoor set built.
Just before the final shootout, Hollister calls to Slade, who jumps up from the boulder he's leaning against and it moves.
"Curly Bill" Brocius is a character in this episode dated June 5, 1883. Brocius was killed by Wyatt Earp on March 24, 1882.