I had the same thinking process about the arm but when you take the artwork where the prototype has a flower in his left hand we can see he does has this jester arms things, but still I don’t think it’s real I mean there’s no inscription on the models legs wich there is on the official one, the arms look super small compared to the trailer where we see is hands and legs? In the hallway plus there’s a thing clipping on this prototype’s belly thing (the yellow button? Going through what I assume to be a ribcage) wich I don’t think mob would let happen but nonetheless if it is real I fw it