Governor Connally's Wrist Wound and CE-399.
The criticality of the bullet is that it is tasked to account for the seven wounds to exclude additional shots and the subsequent explosion of the lone gunman theory.
The trajectory of the rear shot with throat exit is likewise impossible with its entry placed at the FBI's measurements, which are corroborated by autopsy measurements.
The throat exit is denied by the Parkland personnel who stipulate it was a wound of entry.