(1) When they released FotR to DVD, they fixed the car in one of the early scenes. In RotK, Aragorn'n'Arwens son has a little hitch in his get-along as he transitions from the forest to the envisioned palace...the CGI timing was a hair off.
(2) Another fix: the reversed playback of the Edoras aerial shot. They have smoke tools in all that computer stuff, and they can fix it so it comes out of the chimneys.
(3) I still think it was Andy Serkis carrying a giant punkin into the Green Dragon at the end...y'all think (or thought?) it was the Deagol actor. We shall see :)
We shall see! - I never noticed the hitch or the bit with the smoke.... We've already missed those shots on this view.... you'll have to tell us!