The "honor killing" law, which provided mitigating circumstances for anyone who killed his "spouse, daughter or sister" (or their lover) upon discovering them "in illegitimate carnal relations", was definitely abrogated in Italy in 1981, exactly 20 years after the release of this movie.
Giovanni Pluchino, who mans the boat for Marcello Mastroianni and Stefania Sandrelli in the final scene, was a correspondent for the newspaper "La Sicilia" and at the time was reporting on the shooting of the movie for his paper. He was chosen for the bit part because he was "young, good-looking and tanned". Pluchino still remembers that for a long time he was the one who cuckolded Mastroianni.
Stefania Sandrelli had problems crying in the scene where Marcello Mastroianni got spat on by Carmelo Patanè's wife for being a cuckold. After many wasted takes and a prompt by an onlooker, director Pietro Germi--with an unlit half cigar in his mouth--got up from his chair, walked over to her and gave her two good slaps. Sandrelli was embarrassed because she had been slapped in front of hundreds of people and really did start crying, and the the scene was finally shot.
Actress and former model Daniela Rocca was deliberately made less attractive for the role of Rosalia. On set Rocca reportedly fell in love with director Pietro Germi and started an unhappy affair with him which eventually led her to attempt suicide.
Stefania Sandrelli said in a 2011 magazine interview that she still has the bikini she wore in the film in her possession.