The DC Movie franchise is moving into a new era now, but that hasn't stopped a loyal cult of fans from keeping the faith over Zack Snyder's run on the DC movie saga - and everything that it could've been. Indeed, in the years since Justice League has been released, Zack Snyder has been slowly be surely letting fans into the cinematic world he would've built. That includes engaging with fan in question-and-answer reveals about his larger, multi-film Justice League storyline - including how Batman v Superman: Dawn of Justice's crazy scene of a future Flash warning Bruce Wayne would've created another timeline in Justice League 2!
New video of Zack Snyder doing commentary for a Batman v Superman Watch Party reveals his breakdown of The "Knightmare" sequence in the film. Specifically, he gives detail about how the "Knightmare" sequence, and the warning to Bruce Wayne (Ben Affleck) from a future Flash (Ezra Miller) would have word-changing effect on Justice League 2:
"I had this idea that in the future when they [The Justice League] are talking about sending Flash back to warn him [Bruce Wayne], that Cyborg would be doing the calculations to send him back and would say 'I have two possibilities of where to send Flash back in time. The numbers point to two moments to warn you [Bruce]... Like if it's right near the moment when this vent might happen - where Lois might get killed, or Bruce isn't able to stop it, however that's happening - it would be important if Flash came closer to that moment so that Bruce could understand the reality of it.
And so in the future Bruce says to Cyborg 'Well, what times would you send me back to...What time right now would you send me back?' And Cyborg says 'I'm leaning toward this.' And Bruce says 'Do the other one, because you already sent him back here and it was too early - so send me to the other one.' So that's how he's able to get him [Flash] back again. Because in the new timeline he goes to a different point in time that's closer to the event that we haven't seen yet in this film."
The explanation of the dual timelines of Justice League has been thoroughly dissected by fans via various reveals and interviews from Snyder. In simplest terms, Justice League 2 would've seen the League get proactive and take the fight to Darkseid - only to lose when Darkseid slaughtered Lois and corrupts Superman with the Anti-Life Equation. That sequel would've reportedly ended with the Leauge scattered and/or hostage on Apokolips, while Darkseid turned Earth into the living Knightmare we saw in BvS. Jutice League 3 would see Flash go back with a better warning to Bruce, allowing him to save Lois, redeem Superman and defend Earth from Darkseid's full-on invasion.
Needless to say, even though the Justice League #ReleaseTheSnyderCut movement would only deliver the first peace of that epic saga, it still represents to symbol of what could've been for a lot fans. Had it been pulled off, the interwoven continuity of Man of Steel, Batman v Superman, and Justice League I - III would been epic.