Deus Ex Machina
There I was, minding my own business on the John Carter (2012) board, when someone brought up the subject of "deus ex machina".....
.....and I immediately thought of Local Hero.
As the townspeople gather and converge on Ben's humble beach house, Mac says, "I think they just want to talk to him....." Before a confrontation can begin, Happer's helicopter appears, lands on the beach, and his arrival quickly diffuses the situation. When we first see the helicopter in this amazingly-shot scene, all we can see is a light in the sky, and the viewer might even be forgiven for expecting an alien invasion. From this point on, everything in the movie changes, and the focus adjusts from "Will the refinery project go forward?" to "Now what will happen?"
Can anyone who has seen this climactic moment think of a better deus ex machina scene in the history of film-making?