I hope I'm not talking out of school here, but I'm sure a lot of people don't know this about Donald, but before he started taking all his great landscape pictures he did a lot of portraits.
Once he had his subject positioned, and to get an "expressive" look on their faces, he would often step from behind the camera, whip open his trenchcoat, then hit the shutter and make an "exposure".
This kind of gives a whole new meaning to the expression " did he use a flash in that picture". A very innovative man indeed.
Apparently, just another of his many talents and tricks.