Elevator John's speech about how boring it is to go up and down all day is an allusion to Douglas Adams' book "The Restaurant at the End of the Universe".
Elevator John is a nod to the original 1985 UK television movie Max Headroom and the later 1987-1988 American Television series Max Headroom starring Matt Frewer, Amanda Pays, Chris Young and Jeffery Tambor for the American Television series and staring Matt Frewer, Amanda Pays, Nicolas Grace, Hilary Tindoll and William Morgan Sheppard for the original UK Television movie.
When John and Chiana are in the carpark and facing off Rygel as the Black Knight. He calls himself King Arthur and Chiana, Patsy. A definite nod to Monty Python and The Holy Grail. Classic.
During the sword fight in the tower with the ogre an adaptation of part of the first movement of Beethoven's Piano Sonata No. 21 ("Waldstein") can be heard.