At the 2006 Berlin Film Festival, director Michel Gondry told that the main location of the film is a house where he used to live 15 years ago.
Bassam Habib gave Michel Gondry the idea for the film when Gondry asked the then 10-year-old Mounier to come up with a bed time story. Literally the next day, Gondry began writing the script.
Michel Gondry didn't use any chroma keys in this film (excepts the one you see explicitly in Stephane TV), but he screened the FX sequence (already done before the shooting with step-by-step method) behind the actors, so that they could see it and not imagine it, which gives them a different way of playing their parts.
The song that Stephane writes for Stephanie is sung to the tune of "After Hours" by The Velvet Underground, which is also featured in the movie's trailer.
Golden the Pony Boy is a reference to the novel 'The Outsiders'. At one point in the novel someone tells the protagonist, Pony Boy, to stay golden.