The SE wampa needs to go. That thing looked horrible! The obvious stuff like Boba Fett's voice reinstated, Vader's line "Bring my shuttle", fix Piett's flipped rank badge at the end, etc.
And for the love of God! There's GOT to be something you can do about the Ian McDiarmid scene. It's like, I want him in there, but the visual looked so stupid. Is there a possibility of making your own hologram out of other Emperor scenes from ROTS or ROTJ and then compositing it with the Vader footage? The transmission can crackle and sputter to hide the lips not matching up. They're in an asteroid field after all. If that's too ambitious, perhaps you could just manipulate the existing image, fix the hood and add shadow to the neck to hide that turtle thing he had going on. It just did not look right at all. Anyway, hopefully you'll come up with something better - and hopefully not the original old lady/chimp thing, 'cause that one doesn't work any more.
Good luck.