Terry Gilliam has talked about how he managed to pull off a convincing transformation from Heath Ledger to Johnny Depp in The Imaginarium Of Dr Parnassus - but refused to give away all of the film's secrets.
When Heath died during filming, director Terry decided to keep the scenes that he had already shot and then transform his character into being played by Johnny Depp, Jude Law and Colin Farrell for the remaining scenes.
He told Vulture of working on the film: "We found someone who was physically very close to Heath. It was a shock; it was like Heath was sitting there. And once he goes through the mirror, we get a wide shot of him. His having that mask on was what saved the day; it's the only way we could do what we did.
"What I found interesting in the first time that Johnny is revealed, so many people in the audience, when the mask is first lifted off his face, they think it's Heath there for a second.
"It was really about being able to copy Heath's movements. Basically, he perfected it. That's what made the two shots that exist before Johnny."
But Terry said that he wanted to keep some mystery about how he had made the transformation look so smooth: "I will say that there's a scene with Heath in the scene, after he died, that's amazing. It's totally convincing. And I won't tell you how we did it."