The superheroes who make up The Avengers are supposed to be saving the world, but from what? Another trailer released today has plenty of new footage from Marvel's megatentpole, but the movie's still playing awfully coy with its baddies: Sure, there's Loki, but why get the whole gang together for a villain whom Thor once dispatched single-handedly? And despite all the explosions we see (on a single Manhattan street), we barely get a glimpse at what's causing them, aside from a brief-but-promising introduction to a space serpent at the very end of this preview. Instead, the Avengers seem content to spend most of their time fighting each other, whether they're engaging in verbal face-offs or physical duels: Hotheaded Thor wields his hammer against Iron Man and Captain America. Well, that's not a very promising start to bromance.