Continuity: When Groucho is officially hired, he removes his hat twice.
Continuity: In the closing seconds of the film, Groucho takes off his hat and puts it up on the tip of his umbrella. When the camera angle changes to a wide shot, he does it again.
Continuity: When Stuffy gets on the horse with the wagon, he is wearing a coat and dark trousers. As jockey he wears white pants and jockey shirt. While he could have lost the coat easy enough, there was no opportunity for him to change pants.
Continuity: When Chico starts playing, the piano clearly shows "Steinway and Sons." In later shots the logo is missing.