A long-standing controversy exists between this film and the Tom & Jerry short The Cat Concerto (1947). Both sides (Warner Bros. and Metro-Goldwyn-Mayer (MGM)) claim that theirs was the original, and the other was plagiarized. Nobody knows for sure who is correct, and it is, of course, entirely conceivable that the similarities are coincidental.
Franz Liszt's Hungarian Rhapsody No. 2 was first used in Rhapsody in Rivets (1941) produced by Leon Schlesinger Studios 5-6 years before this Warner Bros. Cartoon Studios short and Metro-Goldwyn-Mayer Cartoon Studios short The Cat Concerto (1947).
At the end of the cartoon, Bugs is mouthing something, but no actual words are heard.