The Harry Potter studio tour shows that the real magic is what happened behind the scenes.
The scenes for 4 Privet Drive were originally shot on an actual street. They only ended up making houses because they didn't have access to the house for reshoots.
The graphics team hand-wrote thousand of letters but then found out that they were too heavy for the owls, so they had to make them again.
Warner Brothers / Via harrypotter.wikia.com
Even then it took the owls six months to learn how to carry them.
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The doors at Gringotts actually work, it took three months to make the door they used for Bellatrix's vault.
Warner Brothers / Via danipanteez.tumblr.com
