Terminator's big shoot-out is in a police station with glass dividers between cubicles. I was opening fire with a machine gun full of blanks, while the effects guy was going to break the glass by shooting steel ball bearings. His device was powered with compressed air, like from a diving tank, and it looked like a full-on rifle. It had a large bore in it and fired bearings the size of your thumb. You get hit with that, it could kill you.
Just as Jim called action, I saw the stunt guys playing the detectives poised to run. And I called "Cut!" Which is something you should never do. That's the director's prerogative, and he doesn't like it when other people say the cool stuff. Jim said, "Peter, what the f**k are you doing?!" And I said, "Jim, Jim. This guy right here, he's diving through the frame right there, isn't he?" Stunt guy nodded. And I said to the effects guy, "And you're shooting there, aren't you?" Effects guy nodded. And I said, "Jim, if he dives into the shot, he's gonna get shot in the head with that steel ball bearing." Stunt guy and effects guy looked at each other. There was sort of a long beat there, and Jim goes, "Oh. Good call."