In return for using the penitentiary grounds of the Sing Sing Correctional Facility, the production made a large contribution to the prison's recreation fund.

Source novelist Peter Maas once said of this movie that it was "one of the worst films ever made".

Producer Dino De Laurentiis acquired the screen rights to Peter Maas' source best-seller in 1969 about three years before the movie premiered. As soon as the production of the movie was announced, producer Dino De Laurentiis said that he started getting a series of telephone calls from unidentified people 'inviting' him to drop the project. De Laurenttis was unavailing of these invites and pressed on with the film's development and pre-production.

The "Cosa Nostra", the Italian criminal syndicate in Sicily, which is also known as "The Mafia", translates into the English language as "Our Thing". Director Terence Young commented that "actually, the word 'Mafia' is never used by Italians because it is a word used only by outsiders. Italians talk about it as the Cosa Nostra, and we show how it came into being". Young stated that the terms "Mafia" and "Cosa Nostra" were both used on the movie's sound track. Moreover, Young maintained at the time of the film's launch that Joseph Valachi was "the only time when an insider in the Cosa Nostra broke his oath and told his story".

Real life husband-and-wife Charles Bronson and Jill Ireland played husband-and-wife characters Joseph and Maria Reina Valachi.

The film was made and released four years after the movie's source non-fiction biographical best-seller book of the same name by Peter Maas had been first published in 1968.

Of filming in New York where certain elements took an adverse view of the production, producer Dino De Laurentiis once said: "We had been shooting for eighteen days in New York when a letter arrived at my hotel. It was on the stationery of the Italian-American Civil Rights League, and it was signed by Anthony E. Colombo. We had by no means finished our shooting schedule in New York, but we started to move the entire company of actors, technicians and equipment to Rome towards evening of the same day".

The nick-name of Dominick Petrilli (Walter Chiari) was "The Gap", who got this alias after losing two front teeth in a fight as a child, whilst the nick-names of Joseph Valachi (Charles Bronson) were "Joe Cargo" and "Joe Valachi".

Director Terence Young once said that "The Godfather (1972) is the most expensive trailer ever made - a trailer for our film [The Valachi Papers (1972)]! Young added that "The Valachi Papers (1972) is no 'spin-off' trying to cash in on the phenomenal success of The Godfather (1972)". Young said, in comparison to that movie, that for this film, "we are really much closer to The French Connection (1971). We are the other side of that coin - you could call us 'The Italian Connection'!".

The film's opening prologue, a quote from Senator Robert F. Kennedy, states: "Crime is a question of criminals. It is not a matter of race, color or religion - Robert Kennedy when Attorney General of the United States".

The seventh of eighteen collaborations of husband-and-wife actor and actress Charles Bronson and Jill Ireland.

The casting call for this picture ran for about five months with over four thousand people interviewed for parts in the film many of them Sicilians. Director Terence Young said in the film's publicity: "With the exception of Charles Bronson and several others, most of the cast are all unknown, and the faces are incredible".

Some one hundred actual convicts worked as extras and background artists in the movie due to a special agreement between the production and the Sing Sing Prison made prior to principal photography.

According to Allmovie, "This film had to be made in Italy, because attempts to shoot in the U.S. were stymied by mob-arranged 'accidents' and protests."

The production suddenly ended its New York leg of the production earlier than scheduled to complete the rest of the filming in Italy. Of the production's move from New York to Italy, director Terence Young said: "We had two units working five hours a day, and finished our five weeks' New York Schedule in three. We were very well treated by the New York Italians . . . [but] . . . It was disturbing to have to leave New York and move to Rome earlier than we had planned. In our eighteen days on location we had shot what we had scheduled for approximately four weeks. I had been hoping we could shoot there for about another ten days. But this is a crazy business we're in. As soon as we made the move to Rome, I began to find special virtues in having made the change".

Star Billing Order: Charles Bronson (1st), Lino Ventura (2nd) and Jill Ireland (3rd), Walter Chiari (4th) and Joseph Wiseman (5th).

The film's director Terence Young once said of this movie: "In The Valachi Papers (1972) we show all the real characters - such as Lucky Luciano, Murder Inc. head Albert Anastasia - and the eliminations which were almost a ritual".

The film's opening prologue was a quotation from Robert F. Kennedy. It states: "Crime is a question of criminals it is not a matter of race, color or religion - Robert Kennedy when Attorney General of the United States".

This is the and final theatrical feature film collaboration of actor Charles Bronson and director Terence Young, after Cold Sweat (1970) and Red Sun (1971).

Final theatrical feature film collaboration of actor Joseph Wiseman and director Terence Young. The pair had previously collaborated on the James Bond film Dr. No (1962) where Wiseman had portrayed the title character.

All of Walter Chiari's dialogue was dubbed by another actor.

The film's closing epilogue states: "After seven years in solitary confinement Joseph Valachi died of natural causes. So did Vito Genovese... ...but six months earlier".

The film's closing epilogue states: "After seven years in solitary confinement Joseph Valachi died of natural causes so did Vito Genovese... ...but six months earlier".