Why did you make the second sun more round in the sunset? Being so low, it ought to be elliptical: https://en.wikipedia.org/wiki/Atmospheric_refraction
Also, I’m not sure the red Artoo recolor is a good idea. I know why you’ve done it, but it looks so similar to Artoo (because, of course, it is) that it’s really distracting. Better to allow the viewer’s eye to focus where it ought (Luke & Obiwan) than to fix a minor issue.
I must atmist I found (not) R2 distracting in that shot, I replayed it a couple of time to understand what had been done. While it does fix that small blocking issue, I’ve gotta say it doesnt feel like its had the right affect. I know its a finished shot so I get its probably something you don’t want to go back to, but if you do, you could try chaning the (not) R2 to a different coloured unit. Like seen in earlier shots. There is one with a black Body and white panels I think, and another that is yellow. But as it stands the chome dome, and white body just screems R2-D2 even if the pannels are red. The only other thing I can think of is to keep (new) R2-D2 in frame a little longer so you have time to spot him.
Anyway beatiful stuff as usual and I had no freaking idea you had added that DS shot, its truely a seamless shot. Just makes me wonder what else you’ve suck in.