In the beginning of the movie, when they're watching TV, there's an equation in the bottom of the screen. These are Einstein's Field Equations and represent the gravitational effects produced by a given mass.
A caricatured Django Reinhardt playing guitar can be seen early in the black and white portion of the film. The film's soundtrack sounds as though it was greatly influenced by Django's music (and he recorded a song called Belleville with Stéphane Grappelli).
The music heard on the soundtrack as Mme. Souza and Bruno follow the ocean liner is from the opening movement (Kyrie) of Mozart's Mass in C minor.
There is also an animated caricature of dancer/singer/performer Josephine Baker, a black American entertainer who left the U.S. in the 1920s because of the virulent racism she encountered and became a tremendous star in Europe. She was very big in Paris and often appeared in shows half-nude, as she did in this film.
The shot we see of a pianist just after the initial Triplettes footage goes awry is a cartoon version of Glenn Gould recording a performance for the CBC.
The pianist Mme. Souza and young Champion are watching on television is a caricature of the famous Canadian virtuoso, Glenn Gould, known for his piano interpretations of Johann Sebastian Bach's keyboard works and for the fact that he would hum along as he played the piano (which can be heard in the film).
The yellow-jerseyed leader of the Tour de France depicted in the film is a caricature of five-time tour winner Jacques Anquetil. It would appear that the year is 1957, the year of Anquetil's first win and the only year he participated which featured a stage finish in Marseilles.
Visible in their apartment are pictures of the Triplets with some period stars including Charles Chaplin, there's also a picture of the Triplets on the beach with Olive Oyl.
"Roberte Rivette", the accordionist who plays her instrument atop a truck while following the cyclists in the Tour de France, represents Yvette Horner, the mega-selling artist who still records albums and plays her accordeon to large crowds in France. Horner recently described her own experiences as very similar to those of "Roberte Rivette" in "Les Triplettes de Belleville": she continued playing her accordeon along the Tour de France route with a big smile as insects ceaselessly were caught in her teeth.
The song performed by Madame Souza in the piano is called Uma Casa Portuguesa (A Portuguese House), and was originally performed by Amália Rodrigues, the queen of Fado music.
The bicycles are all computer generated and traced, because the director, Sylvain Chomet, did not believe it was worth the time to get the look of the bicycles "perfect". The figures on the bicycles, however, were only thin lines in the computer generated originals, allowing the animators to breathe life into them.
In bonus footage on the DVD of this film, the director, Sylvain Chomet, indicates that he tried to imitate the stance and walk of tall basketball stars in the triplets.
The song heard in the background of the barbershop sequence (listed as the "Barber Song" in the closing credits) has lyrics in Italian, which are actually complete non-sequitur gibberish referring to food, clothing, Fellini movies and other words that a non-speaker of Italian would find difficult to follow.
In the opening sequence (at the Theatre) Les Triplettes sing a song in what you can think should be the golden period of les Triplettes-style music. With Les Triplettes you can see the performance of Spike Jones (1911-1965) as the director of the band, Django Reinhardt (1910-1953) as the guitar soloist, Josephine Baker (1906-1975) dancing some movements of her most famous "Danse Sauvage" and Frederic Austerlitz Jr. aka Fred Astaire (1899-1987) in a tip-tap dancing piece.