The original French title for this movie, L'écume des jours, translates literally to "the foam of the days" but more colloquially means "the froth" or "the remnants" of daydreams. The English-language title, Mood Indigo, is the title of a 1930 jazz composition by Duke Ellington, the musician who is often mentioned in this movie.
The name of the writer with whom Chick is obsessed, "Jean-Sol Partre," is a spoonerism for the name of one of France's most famous philosophers and authors, Jean-Paul Sartre.
This film is based on a novel written by the famous French writer Boris Vian, who was a jazz music passionate and also a singer.
Paul McCartney plays bass guitar on 4 tracks of the soundtrack. He also contributes to several scenes of the film : for example, he uses his bass to make the sounds heard when Colin plays with the sun rays as they were guitar strings.