For the role of Pierre Morhange (Jean-Baptiste Maunier), the filmmakers chose to hire an actual boys choir soloist. Jean-Baptiste is the soloist of Petits Chanteurs de Saint-Marc, the choir who also sang the songs in the film.
Actor, co-producer Gérard Jugnot mortgaged his Paris apartment to help finance the film. The bet paid off, and he ended up making over 5 million euros for 'Les Choristes' as actor and co-producer. He earned the title of the highest-paid French actor in 2004, overtaking Jean Reno and Gérard Depardieu.
Shortly after the movie, Jean-Baptiste Maunier quit Les Petits Chanteurs De Saint-Marc because he had trouble with the conductor Nicholas Porte that was saying over and over again than no one is irreplacible.