I'm going to have to agree with Vaderios and others. It's a 8000-19000 meter (5-12 mile!) long ship, but from the reused hallways it looks like the entire movie takes place in about 2000 square feet. We never see anything from the interior to make this look like the huge ship it is. Maybe a change in hallway outside Vader's personal bunk would help that out.

And if there's all those officers outside, why couldn't they tell Vader about the energy shield? I guess that Vader doesn't recieve calls in there, that's why someone had to go tell him personally, then he calls Ozzel from there. It would help Veers' (right?) nervousness if there is no one around to help him if Vader decides to kill him.