I never really saw the throne room as "set-like", but maybe it is.

Return of the Jedi does have a number of silly flaws. One of the biggest ones is the explosion Han and Chewie set off. The come running out of the bunker and stand clear, watching and waiting for the explosion, and BOOM. The thing explodes, camera zooms out, and we see the thing exploding big time, Han and Chewie shoudl have come out of their charred, hairless and in little pieces. Too busy making a huge and attractive explosion to realize what a dumb logical error it was.

So yeah, I very much agree with you. Many little things like snuck by in that film.