Continuity mistake: When Lou is finally convinced that he won't get hurt being the umpire in the "Hit The Umpire" game, he runs to take his place then stops in front of the batter. As Lou runs to take his place he isn't wearing a baseball cap, nor is he holding one in his hands, but in the next shot, when he gets hit in the head by the batter, one has mysteriously appeared on his head.
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 Donald takes off his chef's hat that was flattened by the iron, you can see that there is a waffle maker on the table, but when Donald blows up his hat in the next shot, the waffle maker has disappeared.
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.
Visible crew/equipment: After the moving candle/ghost incident involving Ferdie and Camille, and before Moose Matson's money is discovered, Chuck and the doctor come running in, and they all start yelling and talking, there is a person (probably a crew member) briefly visible in the round window in the door in the background.
Revealing mistake: A scene in which a group of soldiers appears to be running uphill was obviously filmed with a tilted camera because all the trees in the background are leaning at a 65-degree angle.