Mr Ghostface said:

Again, the rendering of the new CG shots is really impressive, but the other "new" shots are just elements taken from other FX shots in the trilogy composited together with the occasional new element. The Death Star reveal is a prime example. The first shot of the Star Destroyer is just taken from Empire and flipped horizontally. It's obvious to anyone who knows these films.

I've watched Star Wars and Empire probablly 200+ times in my largely misspent life, and I had NO IDEA that's how he did it.