Again, don’t take me wrong, I’m simply exposing my point of view.
I don’t think it really matters why they are. Who knows? The Death Star has been in orbit for minutes. Maybe they all understood what was going to happen (Bail went back to Alderaan to inform them about the DS), and they are panicking.
About the explosion, I tried to add something like an explosion in the background, but the camera is moving in the Naboo shot, so it always looked like sh*t. At the end I chose to create that white-to-green effect…
Anyway, THANK YOU both for the suggestions, I’ll surely go back to that.