 If you listen closely in the beginning of the general store scene,  you will hear someone singing. It sounds very much like Eric Cartman  singing a line from "Shpadoinkle Day", but is actually Trey Parker  doing the voice of the woman leaving the store. The woman was played  by Brody McHugh (qv), the sister of Jason McHugh (qv), who  played Frank Miller in the film. Jason also filled the roles of  publicist, producer and executive producer.