Continuity mistake: When Oliver is running away from the sliding piano crate on the steps, you can see the crate has its back facing the camera. But when he is run over by the crate, it is now facing the front.
Continuity mistake: When Oliver falls into the fountain with the wooden crate, you can tell the crate is empty because it is floating. But when we see a close-up of Oliver in the next shot, the crate has been weighed down and is not floating.
Continuity mistake: When Stan pokes Oliver in the eye, Oliver steps backwards and you can see the floor around him is saturated with water. But when we see Oliver putting his shoe into the nails on the piece of wood, the floor is now completely dry.