I agree, having covered this aspect in a different thread here. My current thought is that what is seen is the trail of blood and tissue from Trump's ear. The bullet may be out of the scene to the right.

In all this, regardless of the speed of the shutter, there is the problem of how the photographer (or camera) knew when to open the shutter. Knowing "something is going to happen" is worthless if the timing must be to the millisecond or better.