Justice League's Zack Snyder has cleared up a DC Extended Universe plot point and explained why Superman swapped his iconic black suit for the standard red-and-blue in Batman v Superman: Dawn of Justice's Knightmare scene.
BvS's Knightmare scene featured an apocalyptic future where Earth was ravaged by Parademons and Superman had turned evil. When asked why he returned to the red-and-blue suit if he was supposed to wear the black one in Justice League, as previously confirmed, Snyder noted the anti-life equation pushed him back to his classic costume.
The Knightmare timeline is something Snyder has admitted he wanted to revisit in his planned trilogy of Justice League movies. It's unclear what happened to the rest of the League, but according to Snyder, he'd had big plans for "Knightmare Cyborg."
As for the costume, Snyder previously said the black suit belonged to the House of El, whereas the red-and-blue one was Kal-El's representation of being a hero. Snyder explained it was "more inclusive" and "friendlier," which is a stark contrast to the idea of his Knightmare appearance.
The black suit has become a talking point of the DCEU and briefly popped up in Man of Steel when General Zod projected Superman's own nightmarish future and a mountain of skulls. As for Justice League, Cavill teased he'd be wearing it before the movie's release, while concept art has so far been the only hint of what it would've looked like on the big screen. That said, the black suit technically made it into Justice League's original release via a deleted scene of Superman walking past the dark threads.
Justice League stars Ben Affleck as Batman, Gal Gadot as Wonder Woman, Henry Cavill as Superman, Amy Adams as Lois Lane, Jason Momoa as Aquaman, Ezra Miller as The Flash, Ray Fisher as Cyborg, Jeremy Irons as Alfred Pennyworth, Diane Lane as Martha Kent, Ciarán Hinds as Steppenwolf, Jesse Eisenberg as Lex Luthor and J.K. Simmons as Commissioner Gordon. Zack Snyder's Justice League will premiere on HBO Max in early-to-mid 2021.