In 2008, production for the twentieth season was put on hold due to new contract negotiations with the voice actors, who wanted a "healthy bump" in salary to an amount close to $500,000 per episode.
En 2008, a produción da vixésima temporada suspendeuse por mor de novas negociacións dos contratos dos actores, que querían un "incremento notable" nos seus salarios ata acadar a cifra dos 500.000 dólares por episodio.