Just a few weeks before the release of this film, Dan Brown announced the new book in the Robert Langdon series titled "Origin." It is expected to be released in September 2017. Something similar happened when Angels & Demons (2009) was released, but in that case, a book was released months after the film, which was "The Lost Symbol."
None of the movies in the Robert Langdon saga have been produced in the order that their corresponding novels by Dan Brown were released. The Da Vinci Code (2006) was made first, but adapted from the second book; Angels & Demons (2009) was the second movie to be released, but adapted from the first book. "Inferno" is the third film to be adapted, but from the fourth book in the series. The third book, "The Lost Symbol", remains unproduced because the studio preferred to adapt "Inferno" instead.
In comparison to The Da Vinci Code (2006) and Angels & Demons (2009), where the music was mostly orchestral with a few cues of electronic music, this film has a heavier electronic content. The music of the three films was composed by Hans Zimmer.
The reason why a sequel took so long to be released was because Sony wanted to film "The Lost Symbol," but the production of that adaptation became too complicated as Ron Howard preferred to only produce it rather than directing it and Tom Hanks would not be returning as Professor Robert Langdon. In the end, the production took too long that the novel Inferno was released in 2013 and Sony decided to produce that adaptation instead and most of the crew of the previous films returned, including Ron Howard as director and Tom Hanks reprising his role as the main character. Today, "The Lost Symbol" production status remains halted.
This film is the second sequel to be directed by Ron Howard. While filming Angels & Demons (2009), he declared he does not like to direct sequels. However, he considered the books not as sequels but as stand alone stories.
In July 2013, Sony set the film for a December 18, 2015, release. However, due to the date clash with Star Wars: Episode VII - The Force Awakens (2015), the release date was moved from December 18, 2015, to October 14, 2016. In early 2016, the release date was moved to October 28, 2016.
Initially, the third book, "The Lost Symbol," was going to be produced without Ron Howard directing, but in 2013, the fourth book, "Inferno," was released and Sony Pictures bought the rights and decided to produce Inferno (2016) instead.
In comparison with the previous two films that focused more on solving codes and riddles and religious against science situations, Inferno (2016) focuses more on moral dilemmas, global diseases, memory loss and character development.
This movie ends with Hans Zimmer's "Life Must Have Its Mysteries" soundtrack, which is very similar to "Chevaliers De Sangreal," the ending soundtrack of The Da Vinci Code (2006), which was also composed by Zimmer.
Months before the release of this film, composer Hans Zimmer played, on his live tour around Europe, the film's new theme titled "Life Must Have Its Mysteries," along with the themes from The Da Vinci Code (2006) and Angels & Demons (2009).
The trivia items below may give away important plot points.
Elizabeth Sinskey tells Langdon that Zobrist suggested mass sterilization as a solution to the overpopulation problem. This is, in fact, what happens in the novel: Langdon and Sienna (who is not a villain in the book) fail to contain the virus, which was actually released sometime in the preceding week; the deadline stated by Zobrist was actually the date at which the entire population would be infected. However, it is revealed that Inferno doesn't kill people. Instead, it triggers a DNA modification that randomly makes one third of the population infertile.
In the film, Sienna betrays Robert and she happens to be Zobrist's lover and wants to continue his work by releasing the virus. In the end, she dies by trying to release the virus. In the book, she also betrays Robert and is Zobrist's lover too, but instead she wants to retrieve the bag with virus and destroy it before the World Health Organization (WHO) arrives first because she does not trust them, fearing they will use it as a weapon. In the end, neither Sienna nor the WHO manages to retrieve the bag and Sienna, reluctlantly, joins the WHO to find a cure.
In every movie in the Robert Langdon series, someone who initially acted as protagonist is revealed to be one of the masterminds behind the conspiracy, and has even been using Robert Langdon (Tom Hanks) to further their own agenda. In The Da Vinci Code (2006), it was Sir Teabing (Ian McKellen); in Angels & Demons (2009), it was Camerlengo McKenna (Ewan McGregor), and in Inferno, it is Sienna Brooks (Felicity Jones).
In the book, Vayentha is ordered by The Consorsium to retreat after Robert hides at the Palazzo Vecchio, but she is later expelled. However, to prove she is capable of doing the job, she continues to search Robert and intends to actually kill him. In the film, she is ordered by The Consorsium to shoot and actually kill Robert when he hides at the Palazzo Vecchio. In both versions, she dies the same way.
In the film, Chistoph Bouchard turns out to be a traitor and wants to retrieve the virus to sell it. In the book, he is named Chistopher Bruder and this plot point never happens; he remains an agent of the World Health Organization (WHO).
In the book, the character Sienna Brooks suffered from physical and mental illness when she was younger and, as a result, is supposed to be completed bald. She is also supposed to wear a blonde wig (which she gives to Robert in one scene as a disguise). The imagery highlights the character's duplicitous nature. In the movie, this character background was not included. Instead, Sienna Brooks is not bald and is in fact a brunette.
This is the only film where we see a love interest for Robert. In the books, the only love interest he has had was Dr. Vittoria Vetta at the end of the book. In the next books, they broke up but apparently still has contact with her.
The majority of the film was shot in Hungary for budgetary reasons, most noticeably the airport scenes and the meeting between Simms and the World Health Organization (WHO), which took place in the now defunct Ferihegy Airport Terminal 1 that was shut down in 2012 as a result of the bankruptcy of Malév, the Hungarian national aviation company.
In the scene where Robert and Sienna are running from Vayentha in "The Hall of the 500," Robert mentions that he is claustrophobic. In The Da Vinci Code (2006), his claustrophobia is cured by Sophie in a part of the film and in Angels & Demons (2009), he walks between a stretch corridor and he seems to be all right. His claustrophobia in Inferno (2016) may have come back in some time before the events of the film. In the book, he is still claustrophobic.
In all three films of the trilogy, Robert Langdon is seen falling into some kind of water system. In The Da Vinci Code (2006), he falls into a well during his childhood. In Angels & Demons (2009), he gets into a fountain to save a Cardinal from drowning. In this film, he falls into a Cistern to help prevent a major catastrophe from happening.
In the film, "The Provost" rescues Robert from Bouchard and explains that everything was fake. He also accompanies the World Health Organization (WHO) to find the virus and is killed by Sienna. In the book, Robert is caught by Bruder and the WHO. "The Provost" explains some part of the events and later is arrested, and the Consortium is decimated.
In the book, there is a comedic moment when Sienna and Robert disguise as rockstars to avoid being seen by the Carabinieri when they escape from Palazzo Vecchio. However, this scene was not included in the film.
A character that appears in the book, Jonathan Ferris, was cut from the film. In the book, he impersonates the doctor that Vayentha seemingly killed at the beginning and later he helps Robert and Sienna to travel to Venice after he finds them at the Florence Baptistry, and for a moment, Sienna believes he has the virus and that he was Zobrist's lover. He also worked for the Consortium.