Star Yves Montand died of cardiac arrest a few days after he had acted out a scene in this movie in which his character also died of cardiac arrest. On his way to the hospital, he said "I know I'm a goner, but it's not serious. I've had a terrific life."
"I.P." are also the initials of actress Isabelle Pasco, director's girlfriend at the time. "5" stands for the movie being the director's fifth one.