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!"