It's still better than a bare greenscreen set with a couple tape marks on the floor. :P

I found it amusing Star Trek Nemesis totally ripped off the Emperor's Throne room. I thought Vader and Palpatine were going walk in on Shinzon and Picard!

Most of the bunker explosion seems to go upward instead of out. IIRC, didn't they cut a few scenes of the rebels fighting their way into the main part of the bunker? There's no real frame of reference as to how far in they were from the "back door" anyway. Unless Lucasfilm has released a detailed blueprint of the Endor bunker of course. ;)