ray_afraid said:

^I agree, it looks great!
Except maybe that rock (?) on the right. It looks superimposed and the shadows don't seem as dark as the shadows in the rest of the shot.
Maybe it was always like this though?

Yeah, it's simply a bad comp. The matte painting never successfully matched the foreground elements.

Here's how Ellenshaw describe the shot in the making of: “I had done squares, almost Mayan-like. I put it together, showed it to George … and he sat there in dead silence, which means he doesn’t like something. Then he said, ‘Would it be possible to make it look more like Ralph’s?’ So I went back and repainted it to make it look exactly like Ralph’s painting. But when we put the painting with the plate of the men walking along the bottom of the frame, it didn’t quite come off as it should. So it was decided to add some foreground foliage that would move on bluescreen, and the whole thing ended up being put together on the optical printer: the VistaVision plate on the bottom, the painting, and then the foreground foliage. And that helped it.”

Still, no matte painting was ever made to stand up to our level of scrutiny. I think it worked the few seconds it was on screen.