I'm just talking from memory. I own the set but I have it put up someplace. Yeah, checking online I remembered correctly and it opens up to release the mini scoop ship thing. You can definitely rebuild it and it wouldn't take too much to add in a real floor.
Basically it's a standard Lego build where it's a, ha, mockup that won't even fit all the figures it comes with. Kinda sucks but you get what you pay for. I remember being more disappointed that RO-GR didn't have any special printing, even on his back piece. Just that little bit extra and they wouldn't do it.