CAPTAIN AMERICA: CIVIL WAR was a pretty major undertaking for Joe and Anthony Russo, not just in terms of the scope of the story they were telling, but actually wrangling the rather large group of actors who took part. Adapting the Civil War story was everyone's first choice, but as Robert Downey Jr. was in the process of negotiating a new deal with Marvel at the time, his involvement in the film wasn't a given.
Faced with the prospect of a Tony Stark-less CIVIL WAR, the Russo brothers told Entertainment Weekly that they were forced to look at alternatives.
It was not a given that we were even going to do Civil War when we were talking about the next movie after Winter Soldier. So there was a period of time when we explored possibilities for Cap stories that did not include it.
While they waited for Robert Downey Jr.'s contract to get sorted out, the Russo brothers began developing a Captain America film which borrowed from a 1970's story by Jack Kirby centering around the Madbomb, an A-bomb type device which used sonic waves to turn everyone in the proximity into mindless zombies.
There was a period where we did discuss a third act that revolved around the Madbomb from Cap mythology. It didn’t have anything to do with Civil War, and if we couldn’t get Downey – in the very, very early conversations before we nailed him – somebody pitched the idea of a third-act that revolved around the Madbomb, which makes people crazy. It almost like zombifies them – but not literally. The charm of the Madbomb is that you turn hordes of people into berserkers. That was the physical challenge that Cap and company would have had to face.
Baron Zemo (Daniel Brühl) would have been the one to set off the Madbomb, which would force Captain America to fight off hordes of frenzied civilians, as well as some of his fellow heroes, in an effort to reverse the effects.
The notion of the Madbomb would have been Cap having to fight civilians and how he would he handle that. We were always trying to put him into these interesting moral conundrums because of his nature. That would have made a compelling third act because if civilians are the antagonists, how could he stop them without killing them?
CAPTAIN AMERICA: CIVIL WAR is set to be released on Blu-ray/DVD on September 13, 2016.