G.I. Joe: Retaliation's Epic Action Scene: Director Jon Chu Breaks It Down

Chu isn't an obvious choice for Joe — his previous credits include Step Up 3D and Justin Bieber: Never Say Never. But Chu had choreography ingrained in his memory. He knew how to work with a fighter, using his or her body in relation to a space, and how a camera can enhance or detract from what is brought through body movement. "I could focus on the message we're trying to send between the action. The actor and the lens. The magic that happens between the two."

"I'm inspired by the actor in front of me and how they walk into a room," Chu says. He points to John Wayne, who commanded audiences simply by appearing. It was all about swagger. With that thought, Chu let his ninjas' moves do the talking. "The camera can destroy that. If it's moving too fast, if it's moving in the opposite direction, if it's moving in a horizontal way — you can mess up what they're doing. Sometimes the best thing a filmmaker can do is do absolutely nothing and get it on film."

For Chu, Joe was all about not playing with toys. "The restraint of not doing something is the key to getting access in a big movie," he says. "I didn't learn it in the beginning — we went for it — and I learned as we went through the process, I had to learn to say 'no.' 'No, let's not do music' when Storm Shadow and Snake Eyes are fighting. As much as the music guys have a huge orchestra and are ready to go. The fight without music was perfect for their fight."

Chu says setting the close combat fight scene in a hallway was restrictive, but fitting. "That moment is all about mano a mano. As awkward as the hallway was, it played perfectly to the storytelling. It's just sitting back — do not try. The shot never lies, filmmaker's lie. Just get the f**k out of the way."

To fully explain his vision for the twisty, turny zipline chase through a set of snowy cliffsides, Chu relied on his inner child to express himself to the creative team. "I had ninja toys," he says. "Couches and chairs representing the cliffside. I had [special effects house Industrial Light & Magic] there with our pre-vis guys and our stunt people and a climbing expert. I showed them what I wanted the ninjas to do … When I look at the sequence, I can see the chairs and lamps."

G.I. Joe: Retaliation employs a good deal of digital effects, but not without a foundation of reality. Terrifying reality. "We shot the ziplining stuff in Vancouver on a zip line that was literally 1,000 feet in the air," Chu says. "It took weeks to shoot. Our stunt guys in skin-tight ninja outfits. Freezing cold."

Of course, not everyone sailing through the mountains got away with a simple jumpsuit. Sorry, Snake Eyes. "[Our stunt man] Couldn't breathe in that Snake Eyes mask because the altitude was so high," he says. "We had to eventually take off the visor so they could breathe. It was a trip."

Besides adding a tangibility to the ninja battle, the Vancouver shoot also provided Chu's team with references that would enhance the CGI work required to pull the whole thing off. "We took those visual cues and tried to plant them into the other parts of the action sequence," he says. "So sometimes the camera would get bumped, or the camera would lose them for a second and catch up. We put in those inflections."

Instead of using entirely digitized ninjas for the scene, Chu opted to shoot real people hanging from wires against green screen. "We wanted to show their weight. How they swung, how they were going after each other." The director's goal was all about losing the shine of a Hollywood blockbuster. "We would then make the camera errors in those as well. Sometimes it would be out of focus. Sometimes snow would hit the lens and melt on the lens. ILM sewed it all up."

Chu feels confident in his exception of the acrobatic fight sequence. "The idea was, if ninjas could fly, what would it be like?" the director says. "Because we have the practical thing of these ropes, it made it more difficult because things had to be kind of possible. We were stretching a lot, but at the same time, it made us more creative. We have these parameters: what would ninjas do to take down another person? I would call that my anti-gravity, Jedi moment."