When Marge gets electrocuted, or if Marge uses her melee attack and gets her hair stuck in the vacuum, a pair of rabbit ears can be seen. These rabbit ears are similar to that of the rabbit characters that appear in Matt Groening's early comic strip, "Life in Hell". Several characters from this comic strip also appear as cameos throughout the game.

Marge having these rabbit ears was part of an early plot to Marge's character, in that she was secretly concealing these ears under her hair, and was actually one of the rabbits from Groening's comic. This was going to be revealed in the last episode of the series, but the team behind The Simpsons considered the idea too ridiculous and scrapped it.
Contributed by KidDivinegon