In Rabbit Rampage (1955)'s conclusion, "Elmer Fudd" claims that he finally got even with "Bugs Bunny". In reality, the first time that Elmer was on the winning side and Bugs was on the losing side, was here in Hare Brush.
The music that Elmer dances to at the end of the short is a musical parody of "The Bunny Hop", which was a new dance at the time.
"Fruitcake Sanitarium - It's full of nuts" - Sign above the entrance gate to the sanitarium.
The music that plays when Bugs first appears in the short was re-used for the title cards for Red Riding Hoodwinked (1955) and Mixed Master (1956). It is unknown if it's an existing song or an original melody.
Alcatraz was still a notorious prison at the time of this short, where many a bad guy ended up. And often, the crime that sent them there was...tax evasion.