When Phineas asks Mitch his name and he answers, "I'm am known by many names throughout the universe, well two mainly, Mitch and some of the guys call me Big Mitch" is like when King Arthur asks Tim the Enchanter "By what name are you known?" and he responds with "there are some who call me... Tim?".
When they attempt to cross Professor Poofenplotz bridge, she requires them to answer three questions, just as where King Arthur and his knights have to cross the Bridge of Death, where each Knight is forced to answer three questions by the bridge-keeper before they can cross the Gorge of Eternal Peril. The use of a Spam-like can also be considered a reference to Monty Python and the Holy Grail, as it's referenced in the song sung during the Camelot scene. "We eat ham and jam and spam a lot!" In turn, Spamalot is the name of the stage musical adaptation of said movie.