9. The Entire Cast - The Seven Samurai (1954)
When it comes to directorial perfectionists, Japanese master Akira Kurosawa was picky enough to make Stanley Kubrick look like a hack - that's to say, he was utterly uncompromising when it came to making his movies as authentic as possible.
Over the length of his long career, that included using real arrows on his cast members in Throne of Blood, setting a castle set on fire with his actors inside it in Ran, and dying an entire water supply black so "the rain looked better" in Rashomon. Woah, right?
One other such instance of Kurosawa's insanity came in the form of the research task that he assigned his cast prior to shooting what is arguably his greatest ever film, The Seven Samurai. To ensure that his actors were well-aquantied ("well-aquantied" is Kurosawa for "expert in") with samurai life, he assigned them all the task of getting into character by means of wearing the outfits on an endlessly loop for three weeks, so that they could "bond" with them. He also mentioned that he wanted them to have that "worn down" look, and that dirt was encouraged. And it worked.
The cast were reported to have bonded spiritually with their characters in unexpected ways over the course of the weeks, and the movie itself went on to become a classic of world cinema. Taxing, to say the least, but we'd certainly prefer to wear a samurai costume for three weeks over being shot with real arrows.
Unfortunately actor Toshiro Mifune, who starred in both Samurai and Throne of Blood, was subjected to both.