When Emma is making a list about everything she likes about François, she says she likes his dimple and that "it's like a second smile". The dimple was actually Gaspard Ulliel's real life scar on his left cheek, a result from a doberman attacking his face with his claws when Ulliel was six years old. Ulliel's obituary in the French newspaper ''Libération'' described him as having the "most famous scar in French cinema".
The scene where Gaspard Ulliel dances to Orchestral Manoeuvres in the Dark's 1980 song "Enola Gay" was improvised. In the film's press kit, Ulliel said that five minutes before filming that scene, director Eric Forestier made him listen to two or three songs and he chose "Enola Gay" and improvised his choreography. The director said he had pre-selected "Enola Gay" because the song is very energetic and also very melancholic.