23 things we learned about the making of 'Captain America: Civil War'

Nine words repeat themselves on screen throughout the movie to trigger a brain control mechanism for The Winter Soldier.

"I think we picked Russian words that sounded interesting. Had some chewiness to it. And then, even when you read them it wasn't, you know, kittens, puppies," said Stephen McFeely.

Markus added that they looked at how the words read in English to "make you think you were watching something cool."

"Captain America: Civil War" pits the two superheroes against one another and if you thought you were supposed to side with one more than the other by the film's end, you were wrong.

Co-director Joe Russo said one of the most difficult things about making the film was balancing Captain America and Tony Stark's roles to make sure each one felt as if they had an equal voice in the film and that their points of view were equally represented.

"By the time we got to the end of the movie you're left with a very complicated choice to make. You couldn't tell who was wrong and who was right and hopefully you left the theater and argued with your friends and family about who was wrong and who was right," he explained.

When the Russos were first asked to make "Civil War," they originally had no idea what the plot for the film would be.

"We spent months in a room going through ideas — one of which was the Mad Bomb," said Joe Russo.

What's the Mad Bomb? Well, the Mad Bomber has been known as a Spider-Man villain. He was a business man who lost his business and then took revenge by, you guessed it, planting bombs. I think they went the better route.

If you were wondering why "Civil War" broke up Pepper Potts and Tony Stark, it was more than just a contract-deal with Gwyneth Paltrow. According to Joe Russo, Stark would not have been able to go after the Winter Soldier in "Civil War" if Potts was in the film.

"We knew where we were going with the character, [and] that we had to motivate Tony to want to kill Bucky Barnes in the third act," explains Russo. "In order for the third act to work correctly, Tony would have to be off-balance."

"The way that we thought we could make him off-balance was by pulling things out of his life, making him emotionally vulnerable. Really emotionally vulnerable," he continues. "So, Pepper is out of his life. It clearly is an issue for him, as you can see, by Robert's performance here."

You can read more on Potts' exclusion from the film here.

"This was influenced by the scene from 'Jaws,' where Brody is confronted by the mother of a boy who was killed in a shark attack off the shore and he now feels great guilt moving forward in the movie because of it," said Joe Russo.

"It was Robert's idea, naturally, to cast her," explained co-director Anthony Russo. "He brought her up for that role 'cause I think he knew how important this scene would be for the character."

"You have to have an incredible actor or actress opposite him to hold the screen," added Joe Russo. "Robert is an incredibly big personality on-screen."

He's in some childhood photos with his sister Wanda in her bedroom.

Markus explained that Zemo originally was introduced during a black auction market. That was how he got his hands on the red notebook full of terms to brain control the Winter Soldier. However, the scene didn't really connect him to the beginning of the film and seemed a bit too much.

"He killed everybody in the auction by gassing the auction. But we just didn't get enough story out of him. It was too mysterious of an opening scene," explained Markus.

"It wasn't specific enough either to who Zemo was as a villain," added Anthony Russo.

It's not just because Paul Bettany looks good in them.

"The intent with that was that Vision is trying to discover how he fits in," says Joe Russo. "He wants to assimilate, he's looking for an identity, he doesn't want to be a singular entity. He wants to see if he can access humanity in some way."

McFeely asked the Russo brothers if Vision went shopping for his clothes and they confirmed that the superhero is creating them himself.

Screenwriter Christopher Markus took it one step further.

"Vision is always naked," he said. "Everything is made from his skin. It's a projection."

Though Chadwick Boseman wore a costume on set, the final look for the character was designed by folks over at ILM in which they painted over Boseman.

Spiro Razatos, who was responsible for the crazy Nick Fury car chase scene in "Captain America: Winter Soldier," was the second unit director on that car scene.

"There were a few test audiences who went, 'I don't want him to cook. What's that about?"

Of course, we found out in the commentary that it was about humanizing the character. It also may not have helped that test audiences weren't seeing a final version of Vision on screen.

"We wanted to make sure in the final episode of season one of 'Agent Carter' that Howard [Stark] said something to the effect of, 'Steve Rogers was the greatest thing I ever did," said McFeely. "It would pay off this idea that maybe he would pursue supersoldier serum all the way into the '90s."

You can spot Scarlett Johansson's stunt double Heidi Moneymaker as a super serum test subject about an hour and 13 minutes into the film. She's not the only one. You can also spot the doubles for Captain America and Falcon in the same sequence.

Most of the backgrounds were put in later.

One of the biggest surprises of the film happened when Ant-Man transformed into his other alter-ego, Giant-Man.

"We needed something that would turn the events of the storytelling, in a way Tony's team would be shocked. It was a big revelation. It was a big distraction that would allow those two [Captain America and the Winter Soldier] to get in that Quinjet," said Joe Russo.

"We had discussed other things," he continued. "We were asked to take Giant-Man off the table at one point. And I think Wanda had blown up all the ... blew up half the airport."

Russo plays Theo Broussard, the psychiatrist hired to interrogate Bucky Barnes, under the alias Gozie Agbo.

In fact, Russo has played another character in the Marvel Universe on screen. He was Doctor Fine in "Captain America: The Winter Soldier," which he also co-directed with his brother.

Zemo listens to a voicemail from his wife throughout the film a few times. Anthony Russo made light of it.

"Joe [Anthony's brother], of course, plays the doctor that he has to dispatch with. So I remember [Daniel] Brühl said to me at one point, he goes, 'So, I have killed your brother and married your wife.'"

Just because he receives a spinal injury halfway through the film, don't expect Rhodey to not appear in future Marvel movies.

"Rhodey is definitely dealing with this moving forward," confirmed Joe Russo.

"This is the kind of experience that changes a person," added Anthony.

Joe Russo explained that while people gripe that no one is ever killed in the Marvel universe, it would have detracted from the main point of the film.

"It's a family getting divorced from one another," explains Joe Russo. "If you were to kill a character, it becomes a movie about a family getting divorced and then somebody dies while they're getting divorced."

"Those are two different stories that you're telling," he continued. "What we wanted people to walk out of the theater with, all of us, was the tragedy of a family falling apart. Not the tragedy of, somebody's dead, which would've overshadowed the tragedy of them falling apart."

The directors confirmed Captain America won't be Captain America in the next film since he discards his identity. If that's the case, who will he be? One idea is that he'll take on the role of Nomad, an identity the hero once briefly took in the '70s, something which the "Civil War" crew was all too eager to joke about.

"All I can say is I really cannot wait to put Chris Evans in the Nomad outfit," joked Joe Russo. "I really, I just ... I can't wait."

His response was met with giggles as the others went along with it for some playful banter.

McFeely: "He just got back from his fitting, right?"
Markus: "Yeah, you cut it all the way down to the belly button."
Joe: "No, went past the navel. There's a lot of character in that chest of Chris'."