1) Marvel initially wanted to hire Robert Downey Jr.'s reprisal of Tony Stark as a small role, with just three weeks of work. However Downey wanted a larger role, which would lead to a bigger payday. Marvel Entertainment CEO Ike Perlmutter was furious over the request, prompting him to order the screenwriters to write Stark out of the story completely. When the deal seemed like it was off the table, Marvel Studios President Kevin Feige pushed to hire Downey, citing that his casting in the film could leave the door open for sequels, new franchises, and dramatic possibilities within the Marvel Cinematic Universe as Civil War could drive future storylines for these films. As a result with Downey's casting, the actor received a substantial payout that includes a backend participation deal and another payout if the film's box office gross succeeds Captain America: The Winter Soldier (2014).
2) The filmmakers describe betrayal as a crucial theme in the film: "We didn't want the movie to be just about politics and people arguing about platitudes.The final act is built around a personal act between Tony and Steve."
3) Robert Downey Jr. and Chris Evans describe the dynamic between Iron Man/Tony Stark and Captain America/Steve Rogers as a marriage: "We love each other, but it's explosive. You're working toward the same goal but you have very different approaches to it. It's blurry and that's what makes it great: no one's right, no one's wrong. It's going to make it even harder for them to come to an agreement."
4) In an interview, Jeremy Renner said this movie will be like an Avengers movie due to a lot of characters involvement.
5) This movie was announced, along with eight others, at a special Marvel event that laid out the franchises plans all the way up to 2019. Initially, the title was revealed to be 'Captain America: Serpent Society', but this was later reneged within the same event as weeks of rumours and leaks were confirmed and it was officially titled 'Captain America: Civil War'. According to Kevin Feige , the ruse was because "...we [didn't want to] blow our wad on the presentation with Civil War right at the front of it."
6) When the production of the film wrapped up, Sebastian Stan and Anthony Mackie raced each other while in their super hero suits.
7) Captain America, Hawkeye, Falcon, Winter Soldier, Scarlet Witch, Ant-Man, Iron-Man, War Machine, Vision, Black Widow, Spider-Man and Black Panther are confirmed to appear. It is unknown if Hank Pym, Wasp, Daredevil, Red Skull, Hulk, and Red Hulk will, but Ruffalo was seen on the set of the film.
Choose Your Side ?
8) Co-director Joe Russo said that "the most powerful shot of the film" was Steve Rogers stopping a helicopter from taking off with his bare hands. The shot was even featured in the first teaser trailer for the film. Russo said Chris Evans worked very hard in the gym to physically embody the character because they wanted to test the limit's of Steve's physical strength. About the shot itself he noted, "On set we had Chris straining against a crane holding the helicopter to get this fantastic shot of his muscles bulging and you can feel the energy and determination as he tries to stop it."
9) The title of this movie was jokingly announced as Captain America: Serpent Society during the announcement of Marvel Phase 3.
10) General Thaddeus 'Thunderbolt' Ross (William Hurt) will return in this movie, marking his first MCU appearance in 8 years (The Incredible Hulk (2008)). Also, he is the only cast member, (besides Robert Downey Jr. - who appeared in an uncredited scene) to return from The Incredible Hulk (2008). It is yet unknown whether or not he will become Red Hulk in this movie however.
11) Ragnarok or Thor's Clone was an integral part of Civil War in the comics but will not be in the movie. However Vision will be in the movie, a similar concept who's also a robot like Thor's clone and is also worthy to wield Thor's hammer.
12) The Black Panther costume is a combination of a practical costume and visual effects.
13) The trailer broke the record previously held by Star Wars: Episode VII - The Force Awakens (2015) for the most views in 24 hours with 64 million views.
14) This movie is the thirteenth film in the Marvel Cinematic Universe, the first being Iron Man (2008).
15) In the trailer, Iron Man orders Captain America to stay down, and Cap answers: "I could do this all day". That is the same answer he gave to a bully who was beating him up at the beginning of "Captain America: The First Avenger".
16) This will be Spider-Man's first appearance in MCU played by Tom Holland.
17) One scene from the second trailer shows Ant-Man being boosted by an arrow from Hawkeye. This is taken directly from the comics, specifically The Avengers # 223.
18) According to the Russo brothers, the title for this movie has been in existence for over a decade.
19) On October 13, 2014, it was announced that Robert Downey Jr. will be joining the cast of this film, and that it will follow the Civil War storyline.
20) After the 'Civil War' crossover event in Marvel comics was complete another big crossover event was 'Secret Invasion,' which revealed that the shape-shifting alien villains The Skrulls had been replacing key people in government and the super powered community for decades, and that they are at least partially to blame for leading to the events of the civil war as a means to soften human society for a full scale invasion. Since the Skrulls are villains of the Fantastic Four, Disney/Marvel most likely can not use them in future films at this time. Also the idea of a "secret invasion" in the Marvel Cinematic Universe is already very close to what happened when HYDRA revealed they grew inside S.H.I.E.L.D.
21) Teams were initially rumored to be Captain America, Winter Soldier, Falcon, Scarlet Witch, Hawkeye and Ant-Man. Iron Man's rumored side included himself, War Machine, Vision, Black Widow and Spider-Man. Teams now confirmed are Captain America, Winter Soldier, Scarlet Witch, Falcon, Hawkeye and Ant-Man. Iron Man's confirmed side includes himself, War Machine, Vision, Black Widow, Black Panther, and Spider-Man.
22) The movie will have two spin off films, Spider-Man: Homecoming (2017) and Black Panther (2018).
23) This will be the first theatrically released film featuring Spider-Man where the special effects for the character are not being produced by another company affiliated with Sony, the rights holder to Spider-Man. Industrial Light & Magic, which handles much of the special effects for the Marvel Cinematic Universe film series, will be producing the special effects.
24) The film was going to feature the Incredible Hulk, but he was shifted to Thor: Ragnarok (2017) and so the filmmakers chose General Ross in the film as a substitute to illustrate the theme of destructive power: "We thought it would be interesting to use a character who had a fanatical anti-superhero point of view, built on experience. He's cornering the Avengers politically now, he's out-maneuvering them.
25) The longest MCU film to date, at 2 hours and 26 minutes.
26) This movie is slated to premiere in the same year as a DC comics movie also revolving around two heroes battling, Batman v Superman: Dawn of Justice (2016).
27) Sixth time Scarlett Johansson and Chris Evans have appeared in a film together.
28) Robert Downey Jr.'s other recurring role is Sherlock Holmes. Cast member Martin Freeman plays Doctor Watson on 'Sherlock (2010)(TV)'. Freeman co stars with Benedict Cumberbatch who shares the role of Sherlock will play Doctor Strange in future films.
29) Chadwick Boseman underwent a vigorous training program to get in fighting shape for the character. While admittedly not a big reader of comics as a kid, Boseman read as many comics as possible for anything Black Panther-related. Boseman also visited South Africa to better incorporate cultural aspects of the country into his role.
30) Robert Downey Jr. and Paul Rudd have both worked with previous Spider-Man portrayer, Tobey Maguire. Rudd appeared with him in The Cider House Rules (1999) while Downey worked with him in Wonder Boys (2000) and a short scene at the beginning of Tropic Thunder. Wonder Boys also featured Michael Douglas, who played Dr. Pym in Ant-Man (2015)
31) The first time Robert Downey Jr. does not appear top billed in a major MCU appearance. Previously Downey's name appears first in the credits for all three solo "Iron Man" films and the two current "Avengers" films.