Continuity mistake: When Stan, Oliver and Mary are running away from Mickey and Lola in the saloon, Stan shuts the security gate on Mickey and you can see that Mickey just runs up to the gate and stops, but in the next shot, Mickey's head is now through the gate.
Continuity mistake: When Stan and Oliver arrive at Mickey Finn's Palace, they are standing in front of their horse, but when they start performing their dance, the horse has disappeared.
Continuity mistake: When Oliver is sitting in the river, his jacket is unbuttoned, but when Stan helps him up, it is now fastened.
Continuity mistake: When Stan and Ollie arrive at Brushwood Gulch, they show Mickey Finn the deed they've got for Mary Roberts, and it has a couple of holes in it from where Stan has been keeping it in his shoe; Ollie even unfurls it to show the camera it's got holes. But in every other shot after that, whenever the deed is shown, it's got no holes in it whatsoever and is perfectly clean.