Trivia: When Olaf just starts to sing "When I Am Older" count for about 10 seconds and watch the fire jump from tree to tree. If you watch the right side of the screen closely at the 10 seconds point, you can see the fire briefly take the form of Mickey's head.
Trivia: Olaf looking for his friends and ending with "Sven? Samantha? I don't even know a Samantha!" may well be a very obscure reference to the BBC radio comedy panel show "I'm Sorry I Haven't a Clue". The (fictional) scorer Samantha is occasionally "replaced" by an equally fictional scorer called Sven.
Trivia: During "Into the Unknown", Elsa spins around and makes a circle of ice. Two other circles briefly appear above it, making a "hidden Mickey".