Continuity mistake: The Lion sees a cat in his orchestra sleeping and looks to the right of his podium (from his perspective). But moments later when the view switches to behind the lion, he is looking at the cat to the left of his podium. (00:04:35)
Continuity mistake: When one of the ghosts scares Donald with chains, Donald takes his net with him when he jumps off. When Donald dives into the chest of drawers in the next shot, he has no net.
Continuity mistake: When lawyer Goodwill is in the secret laboratory, he picks up a bottle that has "Jekyll and Hyde Juice" written on the label, but when we see him with the bottle in the next shot, the words have disappeared.
Continuity mistake: When we see the animals change seats at the start of the cartoon, you can see there is an aisle in the middle of the theatre, but when the show begins in the next shot, the aisle has disappeared.
Continuity mistake: When Porky arrives home, you can see a window looking outside to the right of the front door, but when Porky shoots the man upstairs a second time, the front door now leads to a hallway with a staircase.