One of the prop chess pieces from Harry Potter and the Sorcerer's Stone
Someone asked; why is this exhibit at the Science Museum, rather than the Museum of Art? I really don't care about such questions; I'm not a museum strict constructionist.
Still, it's an interesting question because a similar exhibit was at the same museum a few years back related to The Lord of the Rings. And the same thing could have been asked about that exhibit, except that - upon reflection - there was a considerable difference between The Lord of the Rings exhibit and this one. The Lord of the Rings exhibit included not just costumes and props, but it also devoted at least half of it's space and exhibits to showing how the movies - and the costumes and props - were made. There were short movie clips, examples of the evolution of character designs, and 3D modeling examples. There was even a fake cart where two people could sit and it demonstrated forced perspective, the effect used to make the Hobbit Frodo appear smaller than the wizard Gandalf.
But you will learn nothing at all about movie making - or even costume design or prop making - at the Harry Potter exhibit, and I couldn't help think the exhibit suffered because of this.