David Fincher meticulously litters the film with subliminal frames and spatial anomalies that expose Tyler's imaginary nature long before the reveal. Before they officially meet on the airplane, Tyler flashes on screen for a single frame (1/24th of a second) four separate times during moments of high anxiety: at the office copier, behind the doctor, at the support group, and as Marla walks down an alley. Once they begin interacting, Fincher's camera blocking strictly adheres to the rules of a single body. When they ride in a taxi or a bus, only one fare is paid. When they pull up to the Paper Street house in a stolen car, Tyler is driving, but the Narrator exits from the driver's side door. Furthermore, when Tyler hits the Narrator in the chest with a chemical burn, the Narrator is holding his own hand. The most telling clue occurs when the Narrator calls Tyler from a payphone; the phone rings back, despite the payphone's printed warning that it cannot receive incoming calls, confirming the conversation is entirely internal.■