The other story I heard was this scene. Gene apparently mentioned to the sound staff to get ready because he was going to go loud and mad. He didn’t tell Charlie. The kid’s reaction of shock was real because they all got a fright when he flew off the handle.
Willy Wonka (Gene Wilder) - You Get Nothing!ALT: Willy Wonka (Gene Wilder) - You Get Nothing!static.klipy.com