Danny's comment on the lifeless Robot Train cars, "What're they gonna do? Rust on me?" is a reference to a line said by King Arthur to the Black Knight "What're you going to do? Bleed on me?"
Danny tricking Freakshow into becoming a ghost is reminiscenet to the Disney film "Aladdin." Aladdin taunts and tricks Jafar into turning himself into a genie, Danny does the same thing to Freakshow only he turns into a ghost. Both villians become more powerful than their previous forms, but they now have a significant weakness for Jafar it was his lamp for Freakshow it was the Fenton thermos.