The final frames, of Daffy on the giant's watch face, is likely a cheeky wink at rival studio Disney's ubiquitous Mickey Mouse watch.
Daffy and Bugs acknowledge the original fairy tale as each breaks the fourth wall.
Elmer refers to a poker game as he first breaks the fourth wall, as in opening with a pair of Jacks.
Bugs' mailbox lists him as 'B. Bunny, Esq.'. In the U.S.A., the title 'Esquire' is usually associated with lawyers.
Giant Elmer is reading 'Little Men' - a play on the fact that he is a giant. Even so, it must be noted that Louisa May Alcott wrote a sequel to 'Little Women' called 'Little Men'.