This marks the second time that Mary-Louise Parker's character has been put in danger either directly or indirectly by Anthony Hopkins' character. The first was in Red Dragon (2002), where Hannibal Lecter reveals her address to the "Tooth Fairy" serial killer.
After the success of the earlier film in 2010, Ernest Borgnine always held out hope he'd be around to reprise his role as Henry the records keeper in the 2013 sequel. When interviewed in April 2012, he mentioned there was talk about it over the years and made one request to the producers - "I told them if they do it, I want to carry a gun this time." He kept in touch with screenwriters Jon Hoeber and Erich Hoeber and in the end would have had a major role in a sequence at the start of the movie. When Borgnine passed away in July 2012, three months prior to the start of production, his scenes were reconfigured and would feature an uncredited Titus Welliver.
During Marvin's 'funeral' there is a Marine Staff Sergeant in attendance. As the mourners are leaving the service, the Staff Sergeant is standing outside the church wearing a US Navy Field Grade Officer's Cover (cap). US enlisted ranks do not have 'scrambled eggs' on the bill.
Anthony Hopkins will play a character called Edward Bradley, a believed dead scientist who created a nuclear weapon. Catherine Zeta-Jones plays a character named Miranda Wood. She is a high-ranked Russian spy and former love interest of Frank. David Thewlis plays "The Frog," a character selling major intelligence for a price. Neal McDonough plays Jack Horton, a character from the Pentagon after the nuclear weapon and Frank Moses. He is the secondary antagonist. Byung-hun Lee plays Han Cho Bai, the best assassin in the world, contracted by Jack Horton to kill Frank Moses. He has a personal conflict with Frank, because Frank betrayed him.
Why did Marvin fire the AK at the helicopter towards the end?
Marvin fires the AK at general area of the helicopter (notice that he doesn't really aim down the sights, he isn't trying to shoot it down or damage it) so it would retreat and get outside the explosion radius. He's making them run away so they survive the incoming explosion.