Continuity mistake: When Tweety goes around the corner of his birdhouse to the washing line, there are initially two pegs on the line but in the next shot there is now one.
Continuity mistake: At the beginning of the cartoon, Sylvester is covered in cuts and bandages. But when we see him in the next shot, the cuts and bandages have all disappeared.
Continuity mistake: At the beginning of the cartoon there is a "Do Not Disturb" sign outside Tweety's house, but when Sylvester is bouncing on the trampoline to get into the birdhouse, the sign has disappeared.
Continuity mistake: When Tweety hits Sylvester with a baseball bat while he is bouncing on the trampoline, you can see that Sylvester is positioned face down but when he lands on the trampoline in the next shot, he is now lying up.
Continuity mistake: When Tweety is running away from Sylvester, he hides in a tube of "Badminton Birds." When Sylvester comes around the corner, you can see there is a racquet next to the tube, but when we see Tweety coming out of the tube in the next shot, the racquet has disappeared.
