Billie Eilish helped the new season of Saturday Night Live get off to a strong start last weekend thanks to her innovative performance of “Bad Guy.” While she sang the song, she appeared to walk around every surface of the room, and now Eilish has pulled back the curtain on how the performance was achieved.

In a new SNL behind the scenes video, Eilish notes that the performance was inspired by a scene from the 1951 Fred Astaire movie Royal Wedding, in which he walks on the walls and ceiling like Eilish did. The clip also shows the technically impressive rig that made the performance possible, a set-up that featured a rotating wheel that contained the “room” inside of it. The camera was fixed to the mechanism, which gave the illusion that Eilish was really defying gravity.