First "Troy & Abed in the morning".
Pierce's napkin drawing of the Greendale Human Being can be seen hanging up behind Dean Pelton's desk.
When Leonard says "baba booey" into the intercom, it is a reference to "The Howard Stern Show".
While wearing the magician's robe, Pierce is called Cookie Crisp by Star-Burns, a reference to the wizard who used to be the mascot of the brand. The joke is further elaborated on when Jeff gets him a wand with a chocolate chip cookie attached to the end of it.