Since the trailer is turned 180° from the towing position I think this must have been staged. Actually I suspect it was photo shopped.
Slick road, trailer starts fishtailing, driver makes a bad move, the trailer comes around on him, he goes off the road, rough ride sends the trailer backwards into the truck bed. It could happen.
Or it could be the guy didn't have a hitch so he's carrying the trailer on the truck bed. People do weird and stupid things.
Or it's a rarely purchased factory option.