The Big Giant Head is mentioned for the first time.
Apparently, the group can speak every Human language.
Harry quotes Hamlet's "to be or not to be" monologue, in which Hamlet is holding a human skull. Harry is holding a bitten apple that looks a bit like a skull. Harry also says he got the speech from "some Mel Gibson movie." Mel Gibson played Hamlet in a 1990 movie version of Shakespeare's drama.
This was one of seven episodes in which James Earl Jones added an unique one-liner to the standard narration under the opening credits. Here, the one-liner is "The earth is covered with a deep, hard crust - although it does have a wonderful, chewy center."