Fourth - There is no historical record of this online (This would have been big news) - the only case of such an accident happening was a magician at a performance cutting his non-related assistant through the middle and he promptly fainted when blood flooded the stage - he was later arrested and taken in for questioning over the incident.
Did you see the dummy head flop out of the center part? Something happened for her not to be able to switch out her head and push the dummy head out...