The music over the end credits is different in this episode than the rest. Starting with "Narcoleptic Scottie", the regular end credits music would be used.
Yvette's doorbell is a variation of the same tune from "Close Encounters of the Third Kind", used to make first contact in the movie.
During the credits after the intro, as well as the closing credits, each cast or crew member's name had a period at the end.