Revealing mistake: When the elephants are making fun of Dumbo in the train caboose, Dumbo's mother pulls a pin which causes the stall door above the other elephants to fall. When the door bounces back up, you can see that the animators forgot to draw the elephants' heads and trunks and only their bodies are visible.
Continuity mistake: When Jerry appears from the hair of the toy lion, you can see that behind him there is a decoration and some purple baubles. In the next shot, the decoration has disappeared and the baubles are now much closer to the lion.
Continuity mistake: When we see from Tom's view the fridge he is going to crash into, you can see the cheese is on the second shelf, but when he crashes into the fridge, it has moved to the top shelf.
Continuity mistake: When Donald has his head stuck in the bowl of food mixture, you can see that the waffle maker has nothing on the bottom plate, but when Donald gets his tail grilled by the machine, another handle has appeared.
Continuity mistake: When Donald uses the jack to raise the hut onto his van, you can see the glass in the window is completely intact, but when he burrows under the hut a few shots later, the glass is now broken.
Continuity mistake: When Elmer puts up his tent at the park, you can see there is a deckchair next to the tent, but when Bugs pulls the tent into his hole in the next shot, the deckchair has disappeared.
Continuity mistake: When Sandy is watching the chef toss hot cakes at the American Grill at the start of the cartoon, you can see there is a jug and some dishes at the far end of the counter, but when the camera pans in on the chef, the jug and dishes are now much closer to him.