Miss Saigon about 20 years ago at the Civic Center in Atlanta. There's a prop helicopter usually used in the fall of Saigon scenes, but on this night a real helicopter flew in and hovered. It was an actual Huey helicopter flown in the Vietnam war, rented for the run of the play. Very dramatic. And there were humorous moments from local frogs, who had decided to visit those pools of water for the duration of the play. Someone came out during intermission and fished some of them out, but the remainder took up their song for the rest of the play.
The play was held rain or shine, and there was a little light rain in the beginning, but everyone stuck it out. There's a youtube film of a demo of the helicopter flight here. It was very dramatic to see it come in at twilight during the play.