In one scene, the Tooth Fairy finds a mouse beneath a pillow and identifies it as "one of us, European division." Ratoncito (Little Mouse) Perez, or "The Tooth Mouse", is a children's book character created by Spanish author Luis Coloma in 1894 said to replace lost baby teeth with gifts in Spain, Portugal, France, Italy, and Latin America.
A post-film dedication appears, "For Mary Katherine Joyce. A Guardian fierce and true." This refers to William Joyce's daughter, who died at age 18 from a brain tumor. The movie was based on Joyce's book series "Guardians of Childhood", which was inspired by stories he told his daughter. MK, the main protagonist in Epic (2013), is based off of her.
Whenever North is surprised or alarmed, he exclaims loudly with the name of a classical Russian composer. For example, he yells, "Shostakovich!'' just before he falls down the rabbit hole, and "Rimsky-Korsakov! That's a lot of eggs!" in Bunnymund's warren (relevant composers: Dmitri Shostakovich and Nikolai Rimsky-Korsakov). This may be an homage to the "Rocky & Bullwinkle" cartoons, where Boris Badenov's favorite expression was "Raskolnikov!," the criminal from Fyodor Dostoevsky's "Crime and Punishment." It may also be a nod to Ira Gershwin's and Kurt Weill's famous novelty song from Lady In The Dark, "Tchaikovsky," the lyrics of which consist entirely of the names of various famous Russian composers, including the ones used by North. In the beginning of the movie, when North is making a train set out of ice, he can also be heard humming to famous Russian composer Igor Stravinsky's "Firebird Suite",
At the beginning of the movie, Jack Frost walks through a Colonial American village. In the background, the folk song village musicians are playing is called "Kempe's Jig." This was a popular early eighteenth century English dance song, named in honor of William Kempe, a famous sixteenth century English comic stage actor, whose work influenced modern comedic acting, stand-up comedy, and improvisational comic skits.
When Jack Frost is kidnapped to North's Headquarters, he calls Bunny a kangaroo. Later on, Frost apologizes for that, to which Bunny replies, "It's the accent, isn't it?" This is a reference to Hugh Jackman, the voice of Bunny, who was born in Australia, known as "the land of kangaroos."
Jack Frost's age has been a debatable subject among the fans. William Joyce, Executive Producer, and author of The Guardians of Childhood series, on which this film is based, has confirmed that Jack Frost is fourteen years old, and wanted Leonardo DiCaprio to voice the character, because he believed he could capture the inner child. During a Q&A on Reddit, Director Peter Ramsey said that he believes Jack to be seventeen years old. Chris Pine was 32 years old when he recorded his lines for Jack.
Bunnymund paraphrases Crocodile Dundee from Crocodile Dundee (1986), as he compares his bag of teeth to Jack Frost's. "You call that a bag of chompers, now this is a bag of chompers," is paraphrased from the famous "You call that a knife..." line.
When Jack Frost, voiced by Chris Pine, who portrayed Captain James T. Kirk in Star Trek (2009), Star Trek Into Darkness (2013), and Star Trek Beyond (2016), refuses to join The Guardians, North says to Jack, "Walk with me." In Star Trek (2009), Captain Robau of the U.S.S. Kelvin, says this in the same fashion to James Kirk's father, First Officer George Kirk, thus promoting him to Captain, before Robau is transported to the Romulan ship to meet his death.