[Editor’s note: The following post contains spoilers for “Avengers: Endgame.”]

Making “Avengers: Infinity War” and “Avengers: Endgame” was a mammoth task for directors Anthony and Joe Russo, but it was even more of a massive undertaking for editors Jeffrey Ford and Matthew Schmidt. The two editors spent two years editing the Marvel Cinematic Universe tentpoles back to back, and they recently revealed to Business Insider that in order to pull off both films they had to figure out what to do with 900 hours of shot footage.

“It was a massive amount of footage with three, sometimes four units working every day pumping out material,” Ford said. “And I’m not even including the motion-capture footage. But if you do a bit at a time you can get through it.”

In order to get both films done, the editing duo had to split up the duties on “Infinity War” and “Endgame.” The Russo brothers shot both movies back to...