"We've worked on the edit all summer and we're excited to finally get these missing pieces in the film and then we expect to be in post through the fall and winter. We hope to be done by March," Anthony Russo said.
The mega Marvel Studios blockbuster ended with half of all life in the universe — including multiple Avengers, Black Panther (Chadwick Boseman), and most of the Guardians of the Galaxy — being wiped out with an Infinity Stone-powered finger snap from Thanos (Josh Brolin), giving the shared Marvel Cinematic Universe its most harrowing ending yet.
"It was so gratifying that in a movie with this scope and scale and that wide of an audience, that we were able to end with a gut punch and yet the audience stayed with us and found value and kept coming back," Russo added.
"It's a rare thing to find in commercial filmmaking and we know it had a lot to do with the the capital that's been built up around these characters for the last ten years of Marvel filmmaking. The audience is so invested in these characters that they're willing to stick with them even through the hard stuff. It has been our great pleasure as storytellers to take them through that hard stuff and have it be a cathartic and even entertaining experience at times."
Punches weren't pulled — not even for revered Marvel flagship superhero Spider-Man (Tom Holland), who was mercilessly dusted in the helpless hands of mentor Iron Man (Robert Downey Jr). Asked about the most surprising reaction earned by Infinity War's shock ending, Joe Russo swiftly pointed to the webhead's tear-jerking dissolution.
"It was probably when a 10-year old boy at a Q&A was crying as he asked us why we killed Spider-Man," he said. "The best reaction was probably that 10-year old kid crying and asking us why we killed Spider-Man. From the time we came to Marvel, our goal was to surprise the audience and not give them the same thing but rather to challenge them."
The Russo brothers, who boarded the MCU with 2014's darker-than-its-predecessor Captain America: The Winter Soldier, followed that hit with the Avengers-splitting Captain America: Civil War, which splintered Earth's mightiest heroes and left the universe vulnerable come Infinity War — a kind of controversy the brothers enjoy leaning into.
"That was our view on Captain America: Winter Soldier, and Civil War was also very controversial internally with the powers that be in turning Iron Man into the antagonist and severing the relationship between Cap and Tony Stark. Every Marvel film we've created had this controversy, like are we pushing this rabid audience too far? Are we making movies that could perhaps be too emotionally complex for the genre?" he added.
"That the audience has shown up wanting more is a testament to the hard work everybody has put in over those last ten years of films."
Avengers 4 opens May 3, 2019.