Trivia

The animators made it so that the Chipmunks frequently scratch their ears to make them seem more realistic.

Comedian David Cross was criticized by his fanbase as well as fellow comedians, notably Patton Oswalt (who, along with Brian Posehn, had been offered and rejected his role in the film) for acting in this movie. Cross responded on his blog where he admitted to taking the role primarily for the money and that he hadn't seen the movie (as he generally dislikes children's films) although he enjoyed working on the film and had "absolutely no regrets at all."

Justin Long (the voice of Alvin) went hoarse frequently during the recording sessions due to the fact he had to pitch up each sentence of dialogue so that the voice altering methods would sound more natural.

Bill Murray, Jim Carrey, Chevy Chase, Tim Allen, John Travolta, Vince Vaughn and Ben Stiller were all offered and declined the role of Dave Seville. Jason Lee states that he was so excited the producers offered him a role they originally offered one of his biggest influences, Bill Murray, that he did back flips.

(at around 24 mins) According to Ross Bagdasarian Jr., the name-sake son of the Chipmunks creator, in an Associated Press interview, the piano seen in the film where Dave and the Chipmunks sing "The Chipmunk Song" is the actual piano that Ross Bagdasarian Sr. used to write and perform the song (as well as "Witch Doctor") that launched the Chipmunks franchise.

Beth Riesgraf: (at around 42 mins) Jason Lee's ex-fiancée, with whom he has a son named Pilot Inspektor Riesgraf-Lee (Pilot Lee), shares a scene with him in the grocery store where they both talk about their troublesome kids.