After looking over those images of the upcoming 2-pack Megatron (the tank, not the dino) I can't help but think that the absence of the right hand was deliberate. In those pics, you can see that where the right hand should be, there is instead a little gray nub (or peg, if you will). Nothing else in the proto pics looks like it'd go there, and they could just as easily have put a hand there; could it be that he has interchangeable hands/fists? perhaps that weren't included with those particular testshots in the photos?? Why would he have interchangeable hands? One solid, one translucent- the solid hand obvioulsy being his normal one, the traslucent could be to simulate something like what the G2 tankmegs had going on with his right hand in the comics: Aside from that, I can't really see any reason why they'd just omit giving him a right hand.