The Taking of Pelham One Two Three1974

Inspector Daniels:
Garber, I just had a terrible thought: suppose they're not on the train? What if they set the throttle and jumped off? While we're chasing the train, they're sneaking out of an emergency exit somewhere behind us.

Lt. Garber:
Ingenious thought, sir, except for one thing: it's impossible.

Inspector Daniels:
Why?

Lt. Garber:
Little gizmo known as a dead man's feature. It was built into the controller handle in case a motorman should ever drop dead. The controller handle has to have a man's hand pressing down on it hard at all times. Otherwise, the thing don't work. The train stops cold.

Inspector Daniels:
Uh-huh. I see.

Lt. Garber:
Nice try, though.