House Easter Egg - Joel Grey Episode

When Dr. House is examining a near comatose patient, a former doctor who preformed unauthorized experiments on his own patients, (Joel Grey) Dr. House lifts up the patient's blanket and says, "Now pay no attention to the man behind the curtain", a quote based from 'The Wizard Of Oz' which Joel Grey repeated in his role as the Wizard in the Broadway show "Wicked"