[Jemian]

Not only must they address how a bullet can change trajectory in mid-air; they also must demonstrate why, if struck from behind, Kennedy jerked backward and not forward.

[Sloth]

why, if struck from behind, Kennedy jerked backward and not forward

Ever shot a watermelon?

[Shooter 2.5]

The impact momentarily pushes him forward.

Look at the film frame by frame.

[elbucko]

Not only must they address how a bullet can change trajectory in mid-air; they also must demonstrate why, if struck from behind, Kennedy jerked backward and not forward.

You haven't been to a shooting range or hunted much. If I told you a lighter bullet in the same gun would shoot lower, you wouldn't believe me. But it's a fact that every good re-loader knows. Bullets can and do some surprising things in flight and in flesh.