The law says that you are responsible for the gun that is in your hand. It doesn’t matter what somebody tells you when they are handling a gun.
He was supposed to go through the steps of opening the barrel and checking the chambers and and everything to make certain that what he is told, in terms of safety, is what the situation.
Being executive producer, that was doubly his job. The responsibility of the EP is to go through all the checklists that need to be checked off that day to make certain that all is well and good.
OK, you're an actor on a set, and you have a scene where you drive a car really fast then slam on the brakes right in front of the camera.
But the car you were given has faulty brakes and when you hit them nothing happens, and you plow through the camera crew and unit photographer and maybe a couple of lighting and sound crew.
Who's criminally responsible for not making sure the brakes on the car were in proper working order? The actor driving, or the film's car wrangler who gave him the keys and a thumbs up?