Continuity mistake: When Sylvester is at the medicine cabinet, he takes out a bottle of Seasick Remedy and starts drinking it. But when we see Tweety in the cabinet in the next shot, the Seasick Remedy bottle is still on the shelf when it should be in Sylvester's hand.
Continuity mistake: When Sylvester discovers that the cupboard door has a lock on it at the end of the cartoon, he is holding a can opener in his right hand, but after we see a close-up of the lock, we return to Sylvester and the can opener has disappeared.
Continuity mistake: When Bugs is making Francois look like a rabbit, he cuts up Francois' moustache to make whiskers. When Bugs says "You make a swell rabbit, Doc!" the whiskers disappear.
Continuity mistake: When Porky Pig arrives at the castle, he appears completely dry. But when he opens the door in the next shot, he is soaking wet, and when we see Porky a few shots later, he is dry again.
Continuity mistake: When we see Junyer Bear sleeping in bed at the start of the cartoon, you can see he has "Junyer" written on the end of his bed, but when he is sitting up a couple of shots later, the word "Junyer" has disappeared.
Continuity mistake: When Raymond Burr emerges from the door at the beginning of the movie, in the first shot he is in the background while Mrs. Van Gelder is dancing. Notice that the decoration to the left of the door frame casts no shadow, but in the next shot the ambient lights have changed so much that now the hanging sculpture projects a huge one. (00:02:50)