Roberto Saviano, who penned the book 'Gomorrah', on which the television series and feature film were based, has been under 24 hour armed police protection for the last decade. Saviano claimed that when the book was first released that gang members passed it around as gifts, but as it grew in popularity his life became under imminent threat.
Actress Christina Donaldio was battling breast cancer during production. Playing tough mafia boss Scianel felt like playing a superhero who helped her feel invincible and motivated her to keep up the fight.
Pietro Savastano is based on Paolo Di Lauro, which ruled Secondigliano and Scampia from 1982 until his capture in 2005. Genny is based on his oldest son Cosimo, who took the reigns (and started the war between the young group and the older group) after Paolo went into depression following the death of Vincenzo, another son of his, in a motorcycle accident.
Salvatore Esposito, who plays Genny, was originally hired as a cue stand-in for other actors who were auditioning for the show. But the directors were so impressed with him that they let him audition himself.