What is that big brown circle thing?
My first thought when I saw it was that it is an aircraft engine with a cover on it but I don't think that is what it is.
otherwise it looks like a big fan with a fabric cover.
As far as the U-turn goes.....i would think that if either Ron/Christina or Nick/Don got to the U-turn that they would U-turn TK/Rachel because they are younger and faster. But on the other hand, I could see if R/C and Nick/Don are neck and neck with each other how one or the other would U-turn the other. It's better to U-turn someone you know is on your tail than someone you don't have a clue where they are.
Also, isn't it Christina who is working on the last task along with Nick and Rachel? that what I have always thought based upon this picture:
Also, I just noticed in the picture of Rachel running she doesn't have on her jacket whereas in the new picture of the big round thing in the background she does have her jacket on.