Continuity mistake: As the orchestra begins playing, the lion is waving back and forth at each side as he conducts the music. In the far shot, his tail is not visible. But when it cuts to a close up of him, suddenly you can see his tail. It is large enough that the yellow tail should have been visible against his black suit in the far shot. (00:02:35)
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.
Continuity mistake: When Goofy searches through the dresser drawers one of the ghosts causes trouble, then Goofy breaks through the top of the dresser and winds up trapped inside, but when all four ghosts appear the dresser top is perfectly fine and that damage has vanished. Also, two of the drawers (one large and one small) fall out of the dresser, but as the four ghosts are pushing the dresser those two drawers have reappeared in their proper places.
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.