Lord of the Rings: The Return of the King - Backward Smoke
At 18 minutes into the movie, we see a helicopter shot flying 'into' Rohan. This was actually a 'fly-out'. Note the chimney smoke going into the house! In a movie with such outstanding effects, why didn't they just add the smoke in post?
I watched the scene of Gandalf and the others riding into Edoras and as the camera moves in closer you can clearly see that smoke is indeed going back into the chimneys of two separate houses.