To be fair, he appears to be joking around with someone across the street by hiding behind the automobile, not falling.
Boy, THAT's a stretch! For one thing, he doesn't HAVE a sense of humor - and a narcassist would never, even in jest, make fun of himself.
I notice the secret service guy in back of him didn't bother to jump forward to help him - how did he know but what he'd taken a shot?
If you look at the windows of the white limo, his white shirt never really goes down very far. He is crouching the whole time and then pops up right as he comes out. The SS guys were likely in on the prank. He didn’t trip, fall, or hit the ground.