In one scene, the Tooth Fairy finds a mouse beneath the 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 and that is 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.
Whenever North is surprised or alarmed, he exclaims loudly with the name of a classical Russian composer - for example "Shostakovich!'' Just before he falls down the rabbit hole; "Rimsky-Korsakov! That's a lot of eggs!" in Bunnymund's warren. (Relevant composers: Dmitri Shostakovich, 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."
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 "Kemp's Jig." This was a popular early 18th-century English dance song named in honor of William Kempe. He was a famous 16th century English comic stage actor whose work influenced modern comedic acting, stand up comedy and improvisational comic skits. He may have performed in some of William Shakespeare's earlier works. He is best known for a stunt where he actually made an entire journey dancing the whole route between London and Norwich (about 100 miles or 161 km).
When Jack Frost is kidnapped to North's HQ, he calls Bunny a kangaroo. Later on, Frost apologizes for that, to what Bunny replies: "It's the accent, isn't it?". This is a reference to Hugh Jackman, who voices Bunny and was born in Australia, known as the land of kangaroos.
When Jack (voiced by Chris Pine, who portrays Capt James T. Kirk in Star Trek (2009)) refuses to join The Guardians, North says to Jack, "Walk with me." Captain Robau of the USS 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.