Several songs used in this episode lead to an in-joke. When Ed and Maria enter a bar the song Lithium by Nirvana plays. When Maria hears how expensive the bagel in the bar is she says never mind to the female clerk. At that point the song stops playing. This is an in-joke since Nevermind is also the title of Nirvana's best selling album and Lithium is one of the songs on it. The song "How Soon Is Now?" by The Smiths plays in the scenes with animal rights activists. This is another in-joke because the band's singer Morrissey is also a famous animal rights activist. The song "Enter Sandman" by Metallica plays during Ed's nightmare. The song "Digging in the Dirt" plays while Ed is actually digging in the dirt for something. The song Shock the Monkey plays while animal rights activists are rescuing lab animals including a monkey.