I am not sure if David Fincher actually hid something in every shot of "Fight Club," but there has been a popular myth circulating on the internet for years.
Some people claimed that Fincher strategically placed Starbucks coffee cups in almost every shot, while others believed that he included a cigarette burning somewhere in each frame.
However, these speculations have been debunked by Fincher himself in interviews. He admitted that he did not intentionally incorporate any Easter eggs in every shot, but he did include some subtle visual cues and motifs throughout the film.
These motifs include hidden phallic images, subliminal flashes of Tyler Durden, and an overall desaturated color palette to reflect the bleakness and emptiness of the characters' lives.