The real Adelina Saulino was a 39-year-old widow when Joseph Petrosino married her -- not a young single girl, as portrayed in the movie by Zohra Lampert, who was 23 at the time.
The real Joseph Petrosino was only 5-foot-3 -- six inches shorter than Ernest Borgnine, who portrayed him.
Though Enrico Caruso was the victim of an extortion attempt by the Black Hand and did actively cooperate with Petrosino, the car bombing incident shown in the film never occurred.