The first rule of Fight Club is that you don't talk about Fight Club. The second rule of Fight Club is that you don't talk about Fight Club. Which doesn't really make a whole lot of sense when you think about it, given that Fight Club is a movie that absolutely everybody should be talking about at every available opportunity: it's pretty much a modern masterpiece. Indeed, David Fincher's brilliantly slick, clinical and biting adaptation of the novel of the same name is continually poised as as one of those timeless movies that - at one point or another - everybody with even a passing interest in cinema has considered as one of their favourite movies ever. After all, it's certainly one of the coolest films ever made. Now, of course, Fight Club has penetrated the mainstream culture to such a degree that even its "secrets" are about as well known as the title of the movie itself. Because everybody on Earth now knows that Edward Norton punched Brad Pitt for real in that infamous parking lot scene, and that Tyler Durden was spliced into various scenes for just a frame. To celebrate the genius that is Fight Club in all of its glory, then, here are 10 very obscure things about the movie that you probably didn't know...