Beavis refers to Hell as "the charred walls of the damned". This is a reference to a heavy metal band formed by Richard Christy named Charred Walls of the Damned. Christy is a huge fan of this series.
Mr. Graham's first name is revealed to be Max, which would mean his full name is Max Graham. This means that his name is an homage to his voice actor, Guy Maxtone Graham.