In the opening credits, the movie is said to be based upon Agatha Christie's "Partners in Crime" featuring Tommy and Tuppence Beresford, but it is actually based upon "4:50 from Paddington."
When Emma Charpentier (Chiara Mastroianni) and Doctor Lagarde (Hippolyte Girardot) kiss for the first time, we can see the boom mic in the window pane behind them.