Overall, the painter style that is your approach was well executed and it seems like you were able to fit in a large amount of characters without whole drawing becoming cluttered or unreadable.
As you point out yourself, there are a few spots be it a person's hand or hair that are a bit flat in colour compared to the rest of the body. It seems like you found most of them, but I'd say that the guy who stands in front of the girl/lady on the bottom right hand corner (with the cybernetic wire going through her neck) has a shirt that is a bit too bright and flat colored based on how you shaded everyone else.
The light source seems to be coming from a rather bright medical style spotlight somewhere above everyone to the left hand side of the screen. Since he is wearing a big medical helmet, and since other people are sort of in front of him, the bottom portion of his shirt would slowly transition to a darker shade since the light is obstructed by said helmet.
You did a good job conveying the brightness, now you just gotta add in some shadows near the crease of his left arm and where the spotlight wouldn't be hitting his shirt.
To the same effect, the girl/lady that have the cyber-wire in her neck has understandable lighting on the left side of her neck, but the right hand side where the wire bends to and where her hair would be covering it slightly, is also just a wee bit too bright. Not as much as the other guy of course, but a tiny bit of extra shadow that shows that her hair is blocking some of the directional light would help add to the depth of the piece, and create some interesting light play and add focus to the fact she has a wire in her neck.
I only noticed it tonight once I finally sat down to write this, it completely slipped past me when I was looking at it a couple of days ago. haha
Lastly, those are some purdy flowers on Ruby's Braids, I'd also just say that the need a smidge more shadow to help nail down the painter-ly realism style you are working towards.
It it isn't laying flat and the lighting is directional, there is going to be some shadows of some kind to add to the depth. :)
Everything else you pointed out already when we were talking earlier, so now I'll just say is that it is a well made drawing and that I like it.
Keep it up Sun! :P