Stage Fright is a 1940 Merrie Melodies cartoon directed by Chuck Jones.
The two curious puppies chase each other into a vaudeville theater after hours. In the backstage the two pups fight over a bone. There, they investigate a stage magician's props. As is expected trouble emerges with the two meeting up with a mischievous seal and bothering a rather cranky resident pigeon. (who lives inside the magician's hat instead of a rabbit)!