"There was a time above..." the opening lines to the movie, align with the future memory Bruce Wayne has, while waiting for Lex's stolen information to decrypt. The papers are violently dashed about the room, as the memory fades(as paper always does right after the Flash leaves), hinting at this sequence being more than just a dream sequence. There is a dimensional reality shown here. Even as we see in Batman's future vision/memory, the rubble of Gotham and surrounding barren crust of the planet, we're being told the population must survive underground. These trucks seem to come out of tunnels. Man has burrowed in to survive, hence 'There was a time above...'
"There was a time above, a time before..." The opening line to BVS, clearly, in light of the message Bruce Wayne recieves from the Flash during his waking dream sequence, validates the fact that the narrator is speaking from the future. That future is one where humanity has gone underground and aliens control the planet's surface. This is also evidenced by the flying creatures that attack future Batman's troops as he trys to steal Kryptonite from Lexcrop.
Pillars of fire are either being forced from above into the Earth's crust and down into its core, or they are somehow being sucked out of the Earth's core, into what appear to be ships hovering, or standing stablized on the surface. The Greek letter for the end, final, is Omega, which is stamped on the surface of the Earth in front of Batman as he is stepping out of an underground bunker. Looking across the very same habor, shown at night previously in Wayne's present, we see what appears to be the rubble of Gotham. Very telling appearances in this sequence, of a struggle on a dying planet between surface invaders assaulting it and driving its inhabitants underground.
The whole sequence points to how in the future, he follows his instincts about Superman's Achilles Heel and acts on it, the Flash even affirms it, almost seedlike in his planting the idea in Bruce's conscience. Listen to how Flash chides himself for somehow, not being able to quite control which time zone he's breaking through to. "AAHHH, no I'm too soon, EEAAH....Bruce, you were right - you were right the whole time......"
We are promised great things with the advent of DC throwing it's hat into the cinematic ring, will DC attempt to flesh out the timeline in their entrance into the comic universe-building game or will they short-sheet us and just chaulk it up to one of Flash's many alternate Earths?
A staple of the comic book industry is the hero mythos: a formula, whereby the character is always birthed in darkness, something so tragic has happened that it has altered his or her preceptions and they are either driven by a 'hero complex', where the voice in their head is calling out, "Help Me!", or they have become embittered and villanous, bent on payback.
I applaud DC Entertainment for staying true to this time honored formula. The Batman was a franchise that, up until Chistopher Nolan, suffered from decades of campiness and attempts to lighten up The Dark Knight's character. Nolan was advised not to purchase the franchise, because it had been so mishandled that it was 'dead'. Director Nolan took the character back to the roots of its origin and painted his cinematic portrayal in deep shades of black & grey. That began the trend of films that we have today, starting Batman back on his original path as Gotham's Dark Knight and brutal vigilante - AS HE SHOULD BE. He was a deeply wounded kid, who felt he didn't do enough to save his parents, so his life has become one of action in compensating for this descrepency. Bravo DC, you've even enabled Batman's shadow to cast a pall over Superman himself, making even THAT boyscout look like a bad guy...
They have stayed true to the formula and it is working for me on the big screen and on the space they have always dominated - television. So please keep on doing it to our heads DC and hopefully you'll cast that pall over Disney's Marvel as well, so that even Mickey Mouse will start to look like the cheese stealing, flea infested, vermin that he is...