In the season 2 episode "I Second That Emotion", Fry, Leela, and Bender are shown around the sewer mutants' village. Fry notices a large gold-plated ICBM on the altar of the cathedral and exclaims "Wow! You guys worship an unexploded nuclear bomb?" to which one of the mutants responds "Yeah, but nobody is that observant. It's mostly a Christmas and Easter thing." The altar and the bomb are a reference to the film "Beneath the Planet of the Apes", in which the religion worship of the subterranean is focused on a nuclear bomb.