Picture of the Year International

That was the cover shot of the December '06 Rangefinder, although it's got the same caption as the web page you linked so there's not a whole lot of info on that shot specifically.  It is a pretty good article. 

In that image the Marines climbed up into the cargo bay and draped the flag while the family gathered around on the tarmac. 

The whole series of images is incredibly powerful.  One has a widow sleeping on the floor in front of her husband's casket so that she could sleep next to him for the last time.  A Marine stood guard all night.  Another has a pregnant widow pushing her stomach up against a casket. 

I can't say if it is or isn't photoshopped/staged, but I do see how it can look like it is.

To be fair, I thought the same thing at first until I read the article that went with it. 

Well, I don't notice anyone's heads going the wrong way...  If I were to guess, I would say you were referring to the man on the far left side.  If that's the case, he is standing and leaning forward to look out the window, probably leaning against the seat in front of him, instead of sitting like the rest of them.  That's why his body position looks different.  Look at it again with a little different point of view, I think you'll see that his head is not actually detached from his body .

And if the plane is done with it's taxi to the gate, then the cabin lights would be on and would be the same light intensity as the lights in the lower compartment where the marines are pulling out the casket, making this exposure absolutely feasible.  It is a totally believable scene in my opinion.  Timing, planning, and a little luck; but that's what these guys live on for these kinds of images.