from the angle it does look as if the elevator is missing but it's there. the trib tab is a function that keeps the elevator at an angle of which you want it to be, sort of like a cruise control. it frees the pilot from applying constant pressure on the pitch controls. that piece broke off, and unfortunately the pilot didnt have enough time to recover.
How small do those things (elevators) get when it comes to racing planes as I am supposing modifications have been made there? I've seen a couple of P-51s before at an aviation museum that one of my friends owns in Pennsylvania and remember the tail section or elevator as you put it looking like any other plane and very distiguishable. In that pic all I can see is the side (metal) of the plane and what looks like a dust/dirt outline and a thin white strip of metal that looks like nothing like which is represented in the pics in this image link below of p-51s from google.... Google pics of P-51s or this video of some similar racing P-51s from what I take is the same racing event in Nevada from back in 2008... <iframe width="560" height="315" src="http://www.youtube.com/embed/3wUsFjTyG8M" frameborder="0" allowfullscreen></iframe>
Tragic subject aside, this is why CF is the best message board on the internet. If you are curious about something, chances are there is a member or three who is an expert. Medical issues? Got it. Plane mechanics? No problem. Want to meet a prostitute at a strip club? Gotcherback.
It is a tragedy, to be sure. But something tells me these air shows need a heavy dose of regulation. How many times are people getting killed at these things. They are up in the air dodging each other at 300-500 miles an hour. How many mid-air collisions have there been?