A person on Blu-ray.com forum said this about the bad shot.

the person involved with the special effects for the restoration was on a podcast a couple of weeks ago and he explained that they did the best that they could do under the circumstances with that scene. He said they were unable to locate the live action footage of the actors against a blue screen. If they had that it would be much easier to lay in a different background that wouldn’t have the problems that the current version does. So basically he’s saying they did the best they could with the time and the money that they had and that it respects the wishes of the original concept and storyboards.

This is disappointing to hear it means it can never be fixed. 😦