Innovation?
I can't remember ever seeing the technique of slamming a body back that has been shot, like the hotel assassination by the pulling of a wire or similar device presumably mimicking how a body would behave on impact. The only other example
I can recall is when little Vito Andolini's mama was shot by the Sicilian crime boss' henchmen in Godfather Pt. 2. Are there others before Bullitt?