Director Zack Snyder and his wife producer Deborah Snyder stepped down from finishing the film, after the suicide of Zack Snyder's daughter in March 2017. They tried to remain on the film as a way to work through the difficulty, but decided after two months to step away from the project to spend time with their family. Joss Whedon, who had signed on for Batgirl, took over as director, managing additional scenes that need to be included in the final cut. Warner Brothers have stated that Joss would direct and write in the same style as Zack so there won't be any tonal shifts or obvious changes in style. However, Joss Whedon controversially fired Zack Snyder's composer Junkie XL, and replaced him with Danny Elfman.
Extensive reshoots in London and Los Angeles in mid-2017 added a cost of approximately $25 million to the film's budget. Henry Cavill worked on the reshoots and M:I 6 - Mission Impossible (2018) at the same time. He had to sport a mustache for his role in the latter project, however Paramount refused to let the actor shave it off for the time he played Superman again. This meant that Cavill's facial hair had to be digitally removed in post-production.
The superheroes are never actually referred to as "The Justice League" in the movie.
Barry Allen says he knows sign language, specifically gorilla sign language. One of the Flash's most famous enemies is Grodd, an intelligent telepathic gorilla.
One of the Gotham scenes during the prologue has a building with "Janus" written on it. This refers to Janus Cosmetics, run by Batman's enemy the crime boss Black Mask. Black Mask is set to appear in Gotham City Sirens.
Ciarán Hinds portrays Steppenwolf in performance-capture. Hinds was unfamiliar with using the technology and got advice from his friend Liam Neeson, who had earlier done performance-capture acting in A Monster Calls (2016).
In October 2007, George Miller had cast the Justice League completely, with D.J. Cotrona as Superman, Armie Hammer as Batman, model Megan Gale as Wonder Woman, rapper Common as Green Lantern/John Stewart, Adam Brody as the Flash/Barry Allen, Santiago Cabrera as Aquaman/Arthur Curry, Hugh Keays-Byrne as the Martian Manhunter (J'onn J'onzz), Tereasa Palmer as Talia al Ghul, and Jay Baruchel as Maxwell Lord. However, the film was shelved during production.
When the film got shown in Iceland (which uses subtitles rather than dub for films with non-Icelandic languages), Jason Momoa's pronunciation of his single line of Icelandic was deemed so unintelligible that it had to be subtitled into Icelandic (often resulting in a big laugh by the audience).
Zack Snyder stated that Justice League was always going to be totally different than Batman v Superman. During the time Warner Bros. invited journalists and bloggers to visit the set, Zack Snyder also stated it was going to have a shorter runtime too.
Billy Crudup plays Barry Allen's (The Flash) father Henry in this film. However, before appearing in the DC Universe, Crudup initially auditioned for and was a top contender for the role of Bruce Wayne/Batman in Batman Begins (2005) before Christian Bale was cast. Crudup also portrayed a DC Comics superhero in the film, "Watchmen."
Wonder Woman first appears in the film standing atop a statue of a goddess. This is the Greek goddess Themis, or Justitia to the Romans, better known in modern society as Lady Justice.
In earlier drafts of the script, Victor Stone was supposed to have suffered his severe injuries as a result of Doomsday's rampage through Metropolis in Batman v Superman: Dawn of Justice (2016).
Due to the running time backlash of past DC movies, Warner Bros demanded a film under 2 hours without credits. The final running time for Justice League is 119 minutes.
Danny Elfman took over from Junkie XL, who originally replaced Hans Zimmer. Zimmer had announced his retirement from the "superhero business" and left to work on Tomb Raider (2018).
Holt McCallany, who plays the burglar in the first scene with Batman, said the scene was written and shot by Joss Whedon as comedic, but Warner Bros. preferred to open the film with a more serious tone, and the scene was re-edited. When McCallany returned home to New York, he found a bottle of his favorite champagne at his door and a note from Whedon that said, 'To battles lost. Gratefully, Joss.' McCallany appreciated Whedon's gesture and had the letter framed.
This movie was initially going to be split into two parts: Justice League Part One and Justice League Part Two, with an alleged singular continuing story line. But by the time filming the idea of the film being in two parts seemed to have quietly gone away, and it is now rumored to be two self-contained movies with two related but separate plots.
Laurence Fishburne was asked to reprise his role as Perry White for a cameo, but scheduling conflicts with other projects made him unavailable on the day filming was supposed to take place.
Bruce Wayne is said to have been operating as Batman for twenty years when the movie takes place. It matches with the 20th anniversary of Batman & Robin (1997).
This film is being released on the same day the animated series Justice League (2001) first aired sixteen years earlier.
The line-up in this film is based on the founding members from the New 52 origin story (with the exception of Green Lantern). During the Silver Age origin story, Martian Manhunter was one of the founding members. He was replaced with Cyborg (who was previously known as a founding member of the New Teen Titans) in the New 52 version.
This film took one decade to come to fruition. A Justice League film entitled "Mortal" was scheduled to be released in 2007, but it got shelved.
In one scene, Alfred (Jeremy Irons) says to Bruce Wayne (Ben Affleck), "One misses the days when one's biggest concerns were exploding wind-up penguins." This is a reference to Batman Returns (1992), where Batman (Michael Keaton) goes up against Catwoman (Michelle Pfeiffer) and the Penguin (Danny DeVito) who had an army of penguins wearing exploding rockets with a plot to destroy Gotham City. The composer of Justice League, Danny Elfman, also composed the original Batman (1989) & Batman Returns (1992) musical scores and he utilizes parts of them in this film.
As an April Fool's Day joke, production said Zack Snyder had left the project and that George Miller would be taken up the directing duties. The feedback was quite positive. However, when Joss Whedon replaced Snyder due to the death of Snyder's daughter, feedback was sincerely sympathetic.
Billy Crudup also starred in Watchmen (2009), based on the DC Comics graphic novel of the same name. Crudup portrays Dr. Manhattan, the most powerful being in existence. Watchmen was also directed by Zack Snyder and while the story took place in a parallel universe to the main DC universe, it appears the current DC comic book Rebirth line of comics combined the Watchmen universe with the current DC main universe.
This film was released on the 25th anniversary of The Death of Superman comic, which was released November 17, 1992; and the 16th anniversary of Justice League (2001) which premiered its first episode November 17, 2001.
This was Zack Snyder's first film shot in the 1.85:1 aspect ratio. This was chosen because Snyder had a great experience with filming the IMAX sections of Batman v Superman: Dawn of Justice (2016) and he "sort of fell in love with [the] giant, less rectangular aspect ratio" of 1.85:1 as opposed to the 2.39:1 aspect ratio used in his previous films.
This movie brings together Batman, Superman, Wonder Woman, Aquaman, the Flash, and Cyborg. Mera shows up in the film, but is not on the team.
This is the third live-action appearance of the Justice League after the failed TV pilot Justice League of America (1997) and Smallville (2001).
Danny Elfman confirmed that he would be using the Batman theme music from Batman (1989) in the film, and would also use briefly John Williams' Superman theme during "a dark, twisted moment" in the film. Gary Clark Jr. and The White Stripes have also been featured in the Justice League album.
Marc McClure who played Jimmy Olsen in Superman (1978) has a cameo as the officer at the prison.
The scene in which Barry Allen/The Flash is grumbling that Bruce Wayne/Batman is sitting in his second favorite chair is an inside joke about "Sheldon's Spot" from The Big Bang Theory (2007). Sheldon is a big fan of The Flash and Cicso Ramon, ally and friend of The Flash also wears t-shirts with Sheldon's quotes in TV series The Flash (2014).
At one point, Warner Bros. considered making this film in performance-capture animation.
In September 2007, George Miller had signed on to direct, but by 2010, he finally left the project.
This is Danny Elfman's twelfth time scoring a superhero film, after working on Tim Burton's Batman films, Barry Sonnenfeld's "Men in Black" films, Sam Raimi's Spider-Man films, Hulk (2003), Wanted (2008), Hellboy II: The Golden Army (2008) and Avengers: Age of Ultron (2015).
Joe Morton who plays Silas Stone in this film and the father/ creator of Cyborg, also starred in Terminator 2 (1991). In both movies he uses futuristic technology that in turn lead to the creation of cyborgs with metal parts and red eyes: the Terminators themselves in Judgement Day, and Cyborg his son in Justice League.
In January 2008, Warner Bros. announced the film was on indefinite hold, allowing options to lapse for the cast. The studio felt the script needed perfecting, which was impossible because of the 2007-2008 Writers Guild of America strike.
The first official footage for this film was shown at San Diego Comic Con on July 23, 2016.
Marit Allen was originally hired as costume designer, but she died in November 2007.
Danny Elfman used a little of his own Batman (1989) score with some key Batman scenes.
When the three DC main heroes (Wonder Woman, Batman, Superman) make their first public appearance in the film, a part of their theme music from their respective films (Batman v Superman: Dawn of Justice (2016), Batman (1989), and Superman (1978) - all their cinematic debut films) plays.
Zack Snyder and Ray Fisher both stated that Cyborg was going to be the heart of this film. However, when Joss Whedon was hired for reshoots, most of Cyborg's scenes were cut.
Back in 2007, Jason Reitman was the original choice to direct the film, but he turned it down, as he considered himself an independent filmmaker and preferred to stay out of big budget superhero films.
Ben Affleck and J.K. Simmons previously appeared together in the films Extract (2009) and The Accountant (2016).
Lana Wachowski and Lilly Wachowski were, at one point, considered to direct this film.
Ben Affleck's third time playing Batman/Bruce Wayne (following Batman v Superman: Dawn of Justice (2016) and Suicide Squad (2016)).
Jason Momoa, Michael McElhatton, and Ciarán Hinds appeared in Game of Thrones (2011).
Henry Cavill's Superman hairstyle got changed from the previous movies. In this movie Henry parts his hair on the left, which is supposedly perceived as masculine and assertive. In his previous movies both Kal-El, Clark Kent had right partitions which was quite opposite of the comic book version.
The members of the Trinity (Superman, Batman, and Wonder Woman) have appeared in 2 movies each before Justice League. Apart from Batman v Superman: Dawn of Justice (2016) which had them together in a live action movie for the first time, Superman was in Man of Steel (2013), Wonder Woman in Wonder Woman (2017), and Batman in Suicide Squad (2016) (cameo).
Ciarán Hinds is the third actor from the Harry Potter franchise to join the DCEU, following David Thewlis (Ares) and Ezra Miller (Barry Allen/Flash). Gary Oldman was another actor to have starred in a DC, as Jim Gordon in the Dark Knight trilogy, but the movies were set in a different universe.
Joe Morton portrays Silas Stone, a character that shares one striking similarity with Miles Dyson, Morton's character from Terminator 2 (1991). In Terminator 2, Dyson is to blame for Judgement Day based on his influence in Terminator development. In Justice League (2017), Stone is responsible for recreating his son into a cybernetic organism. Both of Morton's characters created pivotal androids, it just happened 26 years apart.
The second time Ezra Miller and Billy Crudup have worked together. The first was The Stanford Prison Experiment (2015).
Joe Manganiello portrays his second comic book character after starring as Flash Thompson in Spider-Man (2002).
When Arthur Curry (Aquaman) is facing the oncoming ocean wave as he stands at the end of the pier, the bottom of the shot shows the outline of his boots jutting out from his legs. The appearance suggests a tribute to the comic book Aquaman who has fins on his costume that jut out from his calves.
This is the third comic-book film saga for Ciarán Hinds, after Road to Perdition (2002) and Ghost Rider: Spirit of Vengeance (2011).
Michael McElhatton and Ciarán Hinds have both starred in Game of Thrones (2011) and films about the King Arthur legend: Ciaran Hinds in Excalibur (1981) and Michael McElhatton in King Arthur: Legend of the Sword (2017).
In an ancient battle scene in between Steppenwolf and ancient Superheroes an Archer is seen. Probably he is 'The Rama' (or 'Ram'), a famous indian God. Rama is also a Superhero of 'Hindu Gods' origin in DC Comics Universe . Once upon a time he was a fellow-warrior to Wonder Woman. Other notable Indian Gods in DC Comics are Vishnu, Shiva, Kali, Ganesha, Hanuman etc.