 Fincher wanted Fight Club to have a new brand of promotional pieces.  Which is why the soap bar became the logo for the film. In fact, in  the beginning, the soap bar was the only thing he wanted on the  poster. But Fox made him change it to include Pitt and Nortons  faces. But if you pay attention to all the different posters,  magazine ads as well as the cover of the movie tie in book, youll  notice a few changes in each regarding the ancient map in the  background. In the official poster, it appears behind Ed Norton. On  the cover of the paperback, it appears behind Brad Pitt. And in the  magazine ads, it appears behind neither of them.