When the bells are heard chiming in the convent, the melody they chime is the traditional plainsong melody of 'Dies Irae' the start of a Latin poem that translates as 'Day of Wrath'. This same melody is also used in the opening credits of Stanley Kubrick's film 'The Shining.
Dean makes a reference to the Disney channel show "The suite life of Zach and Cody". Kim Rhodes, who will later come into the show in season 5 and play Sheriff Jody Mills, played the mother in the show.
When Dean asks Zachariah what will happen to Sam, Zachariah replies, "Marsha, Marsha, Marsha!" He is making a reference to the fictional oldest daughter, Marsha Brady, from the classic TV sitcom "The Brady Bunch" (1969-1974).