Visible crew/equipment: When Oliver starts walking down the steps to see the policeman, the piano crate starts sliding down the steps after him. You can see the shadows of the camera and crew on the side of the crate when it slides past.
Continuity mistake: When Oliver introduces Stan to Harry at the snack bar, you can see that Harry's right arm is by his side but in the next shot it is resting on the counter.
Continuity mistake: When Oliver pulls down the chimney pipe from the stove, he is hit by a cloud of soot. At this point, you can see that the top of Oliver's hat is clean, but when Stan appears in the next shot, his hat is now covered in soot.
Continuity mistake: When we see Oliver reading his newspaper at the beginning of the short, the door behind him is open. In the next shot, the door is closed, and in the following shot, the door is open again.
Continuity mistake: When Arthur Houseman takes out the water from the jug and replaces it with gin, you can see there are two glasses in front of the jug, but when we see him pouring gin into the jug in the next shot, the glasses have changed position.