A number of people watched Oswald fire out of the window. That's where they had the description of the color shirt he was wearing. One of the observers was the photographer who took the picture of Ruby killing Oswald. He was out of film.
The back wound coincided with holes in Kennedy's clothing measured by the FBI as follows:
5-3/8" down from the coat collar;
5-3/4" down from the shirt collar.
The hole in Kennedy's back did not go deeper than the first joint of the autopsist's finger.
The hole in Kennedy's throat was identified as a wound of entry at Dallas Parkland Memorial.
The attempt to create a through and through shot from the neck through the throat was a failed hoax.