In turn, each of them would run and jump into a massive fireplace, vanishing from the Ministry of Magic via the Floo Network. The fireplace itself would be added digitally later, so they were running toward a giant green screen and landing on a green crash mat. “It seemed the best way to go out, because it was physical,” director Yates said. And symbolic as well. Free-falling. Taking a leap.
It will barely register in the film - mere seconds of screen time - but as their final act, after a decade of childhood spent in their own ministry of magic, they each ran, and leapt, into the great green unknown. “It was really strange,” Watson says. “And then it was wonderful.”
-Entertainment Weekly