Initially, Ross Bagdasarian Jr. and his wife portrayed Alvin, Simon and Theodore in the film, but were replaced at the studio's insistence with younger actors Justin Long, Matthew Gray Gubler and Jesse McCartneyrespectively (However, Ross Bagdasarian Jr. does provide Alvin's singing voice.) (imdb.com)
Jason Lee's ex-fiancÃ©e Beth Riesgraf, with whom he has a son named Pilot Inspektor Riesgraf-Lee, shares a scene with him in the grocery store where they both talk about their troublesome kids. (imdb.com)
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." (imdb.com)
Dave's house number is 1958, the year Ross Bagdasarian created the Chipmunks and released "Witch Doctor" and the "Chipmunk Song." (imdb.com)
Ross Bagdasarian Jr. was originally set to portray David Seville; however, due to his age (58 at the time of filming), the younger Jason Lee was chosen. (imdb.com)
According to Ross Bagdassarian Jr., the name-sake son of the Chipmunks creator, in an Associated Press interview, the piano seen in the movie where Dave and the Chipmunks sing "The Chipmunk Song" is the actual piano that Ross Sr. used to write and perform the song (as well as "Witch Doctor") that launched the Chipmunks franchise.
Dave`s house number is 1958. 1958 was the year Ross Bagdasarian Sr. created the Chipmunks and released "Witch Doctor" and the "Chipmunk Song."
In some areas, release prints were delivered to theaters with the fake name `Simon` -- which is the name of one of the chipmunks.
In some areas, release prints were delivered to theaters with the fake title `Hairy Beast`.
Justin Long (the voice of Alvin) went hoarse frequently during the recording sessions due to the fact they had to pitch up each sentence of dialog so that the voice altering methods would sound more natural.
One of Jason Lee`s original professional stereo skateboard decks can be seen leaning up against the wall in Dave`s house after he arrives home from his meeting with the music executive.
Bill Murray, Chevy Chase, Tim Allen and John Travolta were all offered and declined the role of Dave. 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.
After the chipmunks are caught lip-syncing, Simon begins dancing a jig. This is a reference to an October 2004 episode of "Saturday Night Live" (1975) in which musical guest `Ashlee Simpson` was caught lip-syncing.
Alvin wears the signature red baseball cap twice in the film.
The car Dave drives throughout the movie is a mid 1960`s Triumph TR4, British sports car.
The phrase the Japanese Alvin doll says ("Konbanwa. Watashi wa Alvin desu") translates to "Good evening. I am Alvin." The Spanish doll ("Hola! Me llamo Alvin y yo quierro un hula hoop!") says "Hello! My name is Alvin and I want a hula hoop!"
In a bit of real-life foreshadowing, in one of Jason Lee`s best known movie roles as that of fictional rock-star Jeff Bebe from Almost Famous (2000), which opens with various street scenes where we hear the Alvin and the Chipmunks Christmas song playing in the background.