“It sounds relatively trivial until you actually figure out how to do it,” Guyett continued. “So we ended up using plenty of miniatures — miniature clock tower, miniature grounds — really relying on graphics and planning. It’s a multi-element shot stitched together with digital technology, but mostly, it depends on old ideas.”

The goal was to realize Cuarón’s vision of a scene that truly “capture[s] the spirit of seeing time reversing itself, circling around you,” and it’s hard to argue with the results. It’s easy to understand the gist of how the trick’s being done on second watch — essentially, Harry and Hermione are being filmed in one take, everyone else is being filmed in another take, then that second take is reversed and combined with the first one — but that doesn’t take away from the magic of the finished scene. The fact that they’re putting all this effort into such a short scene, combined with how the camera never stays still at any point throughout it, really helps to underline just how much the people involved truly cared. 

“Prisoner of Azkaban” is filled with shots like these, including multiple moments where the camera seems to pass through mirrors, that feel almost like the movie is casually showing off. “I’m doing something this cool just on a whim,” Cuarón seems to be telling us with, among other moments, that early two-minute long take in the Leaky Cauldron. “Just wait for what else we’ve got in store.”