Continuity mistake: When the two men talk in the tent at the beginning, watch when one turns around - there is a clear cut in mid action where the men's positions change without any movement. (00:13:05)
Continuity mistake: When Chico and Harpo bring Groucho ice in his office at Huxley College, Harpo is wearing some kind of earmuffs. Between shots they change from going round his chin to behind his head.
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 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.
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 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 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 Harold climbs in the window of his house, his car rolls away to the right. After hearing the crash, he runs back to the window and looks out - to the right, where he sees the wreck. But that's the wrong direction. From inside the house, the wreck should be to the left. (00:08:00)
Visible crew/equipment: When Dr Moreau is showing Parker his plant experiments there is a moment, just after Moreau says "That's one there", when the camera moves past a pillar and the shadow of some equipment is cast on the pillar. (00:30:28)
Continuity mistake: When the Baron is dead and Mr. Kringelein enters in the room, he kneels by him and says a few lines about him looking peaceful. His left arm is on the chair in a position different from the shot before and after, where the hand is at the end of the armrest.
Continuity mistake: The natives approach the ship; one in particular is shown swimming putting her feet right against the bow. One of the crew members pours their drink in the ocean; there's a sailor that walks behind him and makes a sharp left turn. Next shot, and the man is gone, but reappears a second later from the original starting point repeating the walk and turn. (00:05:30)
Visible crew/equipment: When Stan and Oliver walk up the steps to their flat after "borrowing" money from the bank, the shadow of a boom mike is following them up the steps.
Revealing mistake: Rear-screen projection is laughably obvious in all the racing scenes here - especially when two side-by-side car drivers carry on a highly-improbable mid-race conversation with the rest of the race cars wobbling badly on the screen behind them.