During the hospital explosion scene in The Dark Knight, Heath Ledger’s Joker delivered one of cinema’s most iconic unscripted moments. As he walks away from the hospital, the detonator seems to malfunction. Ledger pauses, fiddling with it in character, before the final blast goes off — the delay wasn’t in the script. The moment was so natural and perfectly in tune with the Joker’s chaotic personality that Christopher Nolan kept it in the final cut. What looked like improvisation became one of th