During an interview to the Italian public television, Vittorio De Sica stated that the movie was shot in 33 days and edited in 10. Producer Moris Ergas wanted it ready for the Venice Film Festival in August. It won the award as "Best Picture".
The real-life con-man who impersonated Della Rovere was named Bertont. In the book the name was changed to Bertone, and finally ended up as Bardone in the film.
As Genoa had been rebuilt since the War ended, sets had to be built at Cinecittà and archival footage was used for rear projection.
Many of Bardone's biographical details, such as his birthplace and compulsive gambling were incorporated from De Sica's own life into the character.
Tinto Brass is an assistant director in this film.