Zootropolis: 24 Easter Eggs & References You Probably Missed
23. Let It Go
When Judy first meets and clashes with Idris Elba's Chief Bogo, he gives her a speech about knowing her place, and how life isn't just a cartoon with musical numbers. Aside from how meta that is, his final remark "let it go" is obviously a very tongue in cheek reference to Frozen.
Carrying on the Big Hero 6 references, the calendar in Chief Bogo's office has a picture of San Fransokyo, the main setting of the superhero animation.