The scene during the closing credits is a parody of behind the scenes footage from an old commercial featuring the Mattress Salesman.
When Bart and Lisa ask Moe, "Is that your family's mattress store?" repeatedly, it is a reference to when Bart and Lisa repeatedly asked Homer "Will you take us to Mt. Splashmore?" in "Brush with Greatness". Also, when they repeatedly ask "Are we there yet?".