The trailer doors are like that likely to give the trailer base mode compatibility with the rest of the base playsets in Earthrise, like Ironworks. The friction hinges on the top of the shield are of the A.I.R. Lock style that is the new line-wide "gimmick" for Earthrise. I would have rather had the normal doors and have the shield be a pull out ramp for the trailer, but Hasbro likes to keep it's "parts count" low nowadays.
Blue eyes is always a yay for me with Optimus, though I can certainly agree that yellow provides a better contrast.
The elbow joints should be red in Optimus, yes, but the dark grey doesn't look bad, at least. Not like the blue plastic elbows we saw in some of the recent Takara Tomy photography!
It would have been nice had they colored in the yellow rectangle on the pelvis. That's a weird omission, but the lack of yellow arrows on the wrists isn't as big a deal to me. That's not a detail from either the show or the original toy. I'd have to do some digging, but I think it's one of those weird things that happened because of the old Studio OX promotional drawings and such, kind of like the silver painted shin vents that should be solid blue like the rest of the lower legs.
The gray panels on the insides of the legs did bother me at first, but they bother me much less so now. I think the additional blue paint apps on the fists and pelvis have helped make that issue much less drastic instead of "one more thing wrong" with the deco.
It would be nice to have Roller with the whole package, but he might be a later Battle Master release, or part of a Micromaster set. There are a few other modern Roller options out there too, like the one that came with Legends Optimus Prime in Thrilling 30.
I think the way this Earthrise Optimus Prime transforms is just fine. The kibble on the back is no worse than what we've seen with other iterations. He's had a big bumper butt before with "Classics," Combiner Wars prime had a bunch of combiner-related compromises, and Siege Prime has a huge flat panel on his back that you can see clearly from the front. The tires in the small of the back I think may be another Studio OX thing, too.