How many times have we seen petrol lit with a cigarette in the movies. It begins likes this: there is a running car which is leaking petrol. The hero, who has already ensured the leak, lights up a cigarette and waits with screwed up eyes till the car has almost gone out of the frame. Then with a stylish flick of his hand, he drops the cigarette to the ground. And then you get this close up: Of a cigarette turning in slow motion and falling on the black tarred road. It lights up a long line of fire leading up to the car, which is usually a white Ambassador in Indian movies, and bham: the whole thing goes up on fire. Usually the sound effects for the entire sequence is carefully composed to give us an impression of reality.
But scientists have now proved that this is impossible. Go here.
I can remember this happening in the Malayalam movie starring Mohan Lal, Vandanam, and the Mel Gibson-starrer Payback. How many more can you think of?