If something should be obvious to the PCs, resist the temptation to have an NPC point it out to them. The players will enjoy it better if they notice the thing and realise its significance for themselves.

Although what usually happens is it gets to the point where they should be slapping themselves for not noticing that thing earlier. Then you can either go ahead and have an NPC point out the obvious, and let them slap themselves, or let them suffer the consequences of not noticing the thing, and let them slap themselves. It's win-win, really.

Transcript

C-3PO: Why aren't those star destroyers attacking? All they're doing is throwing PIEs at us.
Lando: Good question.
R2-D2: They were no doubt caught flat-footed by our attack.
[SFX]: < whirr boot doosquee poppy >
Nien Nunb: Mon Mothma has beautifully flat feet. At least I think so. She has the poise of a dancer.
[SFX]: Pow! Pow!
Leia: This guy should be glad I'm not in communication with him, or his bubble would be so burst it's not funny.
Nien Nunb: <sigh>