Was one of several films around the world that were the first to use an entirely "digital backlot" (i.e. the actors were all shot in front of blue- and green-screens with all the backgrounds added in post-production, a technique which has been used for TV, video and video game production for many years). Fans debate on which movie was shot first, but the other movies include: Sky Captain and the World of Tomorrow (2004), Casshern (2004), and Sin City (2005).
(at around 1h 30 mins) The book that Jill is reading in Paris is "Les Fleurs Du Mal", by Charles Baudelaire. It talks about paradise, love, death, time, exile, among others themes, all referenced during the movie.