1) Tyler appears in the film at least four times before the Narrator glimpses him on the moving walkway in the airport. In the four appearances, Tyler flashes onscreen for just an instant and is only visible when the Narrator has insomnia:
a) At the photocopier at work;
b) In the doctor's office, when the Narrator is learning about the testicular cancer support group;
c) At that group's meeting;
d) As the Narrator sees Marla leaving a meeting but doesn't follow her.
2) The Narrator says I know this because Tyler knows this.
3) At the airport, the Narrator says "Could you wake up as a different person?" and the camera follows Tyler.
4) For a brief moment in the beginning of the film, the Narrator can be seen as Tyler's reflection in the window.
5) Early on, we see the Narrator getting off a bus with one of the Project Mayhem folders.
6) The Narrator wanders the house while Tyler and Marla noisily have sex upstairs. When the detective calls and the Narrator answers the phone, the sounds of the lovemaking instantly stop.
7) When the airport employee "lends" Tyler the car, the Narrator and Tyler get in through the same door. After the crash where Tyler was driving, Tyler pulls the Narrator out of the driver's side of the car.
8) When Norton fights himself during the scene with his boss he says that he thought of his first fight with Tyler.
9) When the Narrator is talking to the doctor about his sleeping problem, he states that he might have narcolepsy, for he sleeps and wakes up strange places that he's never been too. Later, he states that Tyler was a night person. In one Scene, Bob(Meatloaf) even says that he has heard rumors that Tyler only sleeps one hour a day.
10) On the airplane the Narrator mentions that they have the exact same briefcase. And although Tyler opens his, we never see the contents of the Narrator's.
11) At the payphone when the Narrator gets a phone call from Tyler, the sign on the payphone reads: "No Incoming Calls Allowed".
12) When the Narrator is traveling, frantically trying to find Tyler, he says, "I had the strangest feeling of Déja Vu, everywhere I went I felt like I'd already been there before."
13) When the Narrator asks the members of Project Mayhem what they did after they vandalized that building and made a happy face on it, they laugh as if he'd just made a joke about not knowing what was going on.
14) When the Narrator threatens his boss, after he finds the Fight Club rules in the photocopy machine, he says to himself, "Tyler's words, coming out of my mouth."
15) When entering Lou's Tavern, the Narrator enters first and the guy out the front only acknowledges the Narrator, as though Tyler doesn't even exist.
16) When going to the Convenience store where Raymond K Hessel works, Tyler gets the gun out of the narrator's bag. The Narrator obviously didn't know the gun was there, indicated by his astonishment "Is that a gun?". Despite the fact that it's his backpack.
17) When the Narrator enters the house prior to seeing the news report of the happy face on the building, he is carrying one of Project Mayhem's folders.
18) When Tyler is about to tell the Narrator about how he met Marla, the Narrator says "I knew the story before he told it."
19) When the narrator gets on the bus with Tyler, he only pays the fare for one person.
20) When Tyler and the Narrator are on the bus, the long-haired guy pushes past Tyler without a word, then says "excuse me" as he pushes past the Narrator.
21) When Marla calls the Narrator, he is surprised, and asks how she found him. She replies that he left her a forwarding number.
22) When the Narrator and Tyler are discussing their fathers, Tyler mentions how his father didn't go to college but expected Tyler to. The Narrator says that sounds familiar.
23) The Narrator claims that if he could fight anyone, he would fight William Shatner. In Star Trek episode "The Enemy Within" (1966),Captain Kirk (played by Shatner) was split into two alter-egos by a malfunctioning transporter; the two alter-egos, each a side of Kirk's personality, fought against each other before Kirk was eventually returned to normal.
24) After the scene in which Tyler asks the Narrator to hit him "anywhere", and the Narrator hits Tyler in the ear, he is seen at the office the next day commenting that life seems to have the volume turned down after a fight.
Thanx to:
http://us.imdb.com/title/tt0137523/trivia