We've told you what we've learned and what we thought was cool, but one appearance in the Batman V Superman: Dawn of Justice trailer is worth noting on its own: our first look at Robin in the new DC Cinematic Universe... well, almost, anyway.
Robin's costume is mounted in what appears to be the very modern-looking Batcave seen in the trailer. Ben Affleck as Bruce Wayne approaches the costume, which is defaced with writing that one must assume comes from the Joker - thanks to all the "HAs" on it.
The costume itself is interesting to analyze. The "R" symbol is very stylized and pointy, and not exactly like any seen in the comics, though close to a couple of them. There are buckles on the chest, and it looks fairly armored. He has his own gauntlets, similar to Batman's, and of course the now-signature DCCU darker color palette. A simple domino mask accompanies the costume, and he's holding an interesting weapon.
While Tim Drake and later Damian Wayne, two Robins in the comics, have been seen often using a quarterstaff, this Robin seems to be holding a halberd of sorts, a staff that ends in a spear, with an axe-like second point just shy of the tip. It's a very brutal and potentially lethal weapon for any hero to use in crime-fighting, especially a street level hero that's actually the kid sidekick to another vigilante.
So what does this mean? Well, in the comics (and animated and video game adaptations), the Joker did (apparently) kill one Robin, the second one, Jason Todd. The defaced costume seems to indicate something similar has happened - and it's possible the weapon he holds isn't his own, but the murder weapon.
Of course, any inclusion of a Robin means we could see a new Robin in the film universe, at least eventually. In the comics, Todd was the second Robin, after Dick Grayson. In current continuity, he was succeeded by Tim Drake (who took the alternate name Red Robin), and eventually Damian Wayne, Bruce's son with Talia al Ghul - yeah, comics get a bit complicated. Does this costume's inclusion mean we'll get some Robin action later in the series, or is it just an Easter Egg? Either way, at least Robin exists... or... existed.
Batman v Superman: Dawn of Justice is in theaters March 25, 2016