As you know, in order to facilitate Frank Oz's performance of Yoda, the Dagobah sets for Empire were basically built on stilts, so Oz could sit underneath and stick his hand up Yoda's hole. This is made obvious in one scene (I can't remember exactly where, and my DVDs are 200 miles away so I can't check) where Mark Hamill steps in between the studs holding up the plywood making the ground, and it visibly bends under his weight. It distracts me every single time I watch the film, and I would really appreciate it if you could take care of that, Adywan. Thanks.
Speaking of Yoda and performances, I think Frank Oz's job with Yoda is just about perfect and doesn't require very much CG touchup. Unlike the bar patrons of Tatooine, Yoda has always been completely convincing as he is.