The plot to kill the Irishman (Danny Greene) involved an unprecedented breach of FBI security when a clerk was bribed by the mob and actually stole a list of confidential informants from a top secret room. Cleveland agents acted quickly, plugging the leak and arresting their clerk.
Danny Greene became such a folk hero in Cleveland that a young admirer penned a ballad in his honor. It reads in part, "...They shot him down and blew him up With most regular persistence. Through guile and luck and skill, Danny Greene is with us still. Some day he'll die, as all we must, Some will laugh but most will cry. His legend will live on for years, To bring his friends mixed pleasure, For he has done both bad and good, And lived his life full measure."
The production temporarily re-opened the retired Tiger Stadium known as Navin Field for approximately one week. The stadium originally opened in 1912 and closed 87 years later when the Detroit Tigers departed for their new facility. The stadium was then demolished after the production completed filming.
Tommy Reid noted that getting mobster Danny Greene's story on film took 12 years. Reid, a native of New Jersey, says he learned about Greene while a student at Ohio State University. Reid went on to buy the options to the book by Rick Porrello titled "To Kill the Irishman: The War That Crippled the Mafia," on which the film is based.