23 Behind-The-Scenes Facts That Prove These Actors Were Perfectly Cast

10. One last HP one — James and Oliver Phelps, who played the Weasley twins, would play pranks on set. In fact, they once pranked Rupert Grint by making him believe there was a whole choreographed dance number in the Yule ball scene that the entire cast knew except for him. "We were like, ”Do you know your steps? You know, right? You know, the routine? Like, we've all been doing a routine for, like, the past six weeks,' or something like that," James said.