Sometimes NPCs know a lot more than the players think they do. Quite a lot of the time, actually, when you really stop and think about it. So make sure and bamboozle them with mind-blowing knowledge sometimes. They can know stuff that the players believe nobody has any right to know.
And the good thing is, you never have to explain how they know it. Leaving it mysterious is much more fun than explaining it.
Nik Sant: And we know who you are. Leia.
Leia: What?! I mean, my name's... Princess.
Nik Sant: But let's not tell anyone, Delevar.
Delevar: If we do, she'll die.
Leia: Who the hell are you people?!
Nik Sant: Professionals.
Delevar: Have you looked at the sky recently? It's important. But don't forget the ground.
Han: Enough of this kookiness. This base isn't going to storm itself.
Chewbacca: He's right. There could be guards coming.
Leia: Right, but we're going to have a serious talk afterwards.