Yves Boisset says in his autobiography that Lee Marvin stayed sober throughout the shooting of Dog Day (1984), despite the fact that he had a solid reputation of being an alcoholic.
After the shooting of the movie, Lee Marvin got heavily drunk and smashed a policeman's face in the streets of Orléans. But he finally apologized to the cop by bringing many flowers to his hospital room.
According to Yves Boisset in his autobiography, "La vie est un choix', despite the fact that they did not speak nor understand the same language, Lee Marvin and Jean Carmet became friends during the shooting of the film.
Gangster wannabe Chim calls himself Aniello Dellacroce, which was the name of an underboss in the Gambino crime family in New York.