There are no computer graphics or digital tricks in the film. Everything you see really happened in real time exactly as you see it. The film took 606 takes. On the first 605 takes, something, Usually very minor, didn't work. They would then have to set the whole thing up again. The crew Spent weeks shooting night and day. By the time it was over, they were ready to change professions. The film cost six million dollars and took three months to complete including full engineering of the sequence.