Avengers: Endgame New Trailer Breakdown: 16 Things You Need To See
6. Ant-Man & Nebula Get Amongst The Action
In what appears to be the same scene as the one with Captain America, we see Ant-Man and Nebula get right into the thick of the action.
What's crucial here, oddly enough, is the pencil that Ant-Man is using as a launchpad. Were it not for that, then the assumption would be that the Avengers are fighting on Titan, but the presence of a pencil (and what looks like some sticky tape too) means this has to be Earth - and most likely New York, because that's where they're based - as otherwise it doesn't make any sense whatsoever.
Nebula, meanwhile, gives us the biggest hint of who they're fighting. Not that there are a huge number of possibilities anyway, but the way she roars into action does hint she's seeing her father Thanos again here, as it's hard to imagine what else would inspire such a reaction. Again, though, that might just be what Marvel want people to think, since so much of what they're doing will be to misdirect us.
It's also worth questioning when this battle is. Time travel is in play, so this isn't necessarily the present. That they aren't wearing the white suits suggests it is, but there's a chance they do change costumes after going back, or that the suits have the ability to hide/cover their other costumes at the press of a button.
If that's the case, and they're in the past, then it would alter who they could be fighting and where they might be. If the purpose is to retrieve the Infinity Stones from the past, then maybe they're on the WWII battlefield for the Tesseract. That's almost certainly just wishful thinking, but imagine how cool that would be.