It’s called hypermobility. I can do that with my hands. 

I think that the hand orientation is correct. Her wrist and hands are just very flexible. It looks like her hands have been stretched in length and this causing the image to look odd.

Because of the location of her fingernails, we have to assume that he right palm is facing downwards. The folds of skin at the wrist look more like what you get when you bend you hand so the palm is facing upwards. Once again I put it to the mirror test, and did get that skin fold pileup when bending my hand so the palm is down. However, her right arm looks like how an arm looks when the hand is bent the other way (there is a hint of the tendons that sometimes become prominent when you do that.) So in the area of the arm from the cuff to the wrist, the arm is telling you her hand is bent back, palm upwards, but the hand itself is somewhat ambiguously saying “palm down.” Part of that ambiguity, I think, is because the back of her hand is cupped slightly, which makes it look a bit palmish. When I duplicate that position, the back of my hand gets quite flat. A younger, more limber person might conceivably have a concave back of the hand when the fingers are aggressively extended. Which they are here. I do think the fingers themselves have been Photoshopically elongated in both hands, along with possibly the hands themselves. I agree about her left arm. It just pops into the frame and looks like it belongs to someone else.