On the last day of shooting, Fred Thomson was badly injured while filming a horse-to-horse transfer in the runaway stagecoach scene. Thomson and a horse both fell to the ground during a turn in the path, and the stagecoach (carrying four crew members and additional weights to keep it steady) drove over him. The scene was finished by stuntman Yakima Canutt and Thomson's fall was incorporated into the scene.
This stunt, which became Yakima Canutt's trademark, was accidental in inspuration due to initial stuntman Fred Thomson's unplanned fall under the horses according to the director and was the start of many of the same planned complete gags by Canutt to boot.