9 There is a Starbucks cup in almost every scene of the movie.

Director David Fincher revealed in an interview that in his 1999 classic, Fight Club, there is a Starbucks cup in almost every scene. When asked why, he said that when he first moved to New York in 1984, it was very difficult to find decent coffee. Then came Starbucks. When Fincher presented the script to Starbucks, they agreed on having some fun by allowing Fincher to put Starbucks references throughout the movie. The only scene they didn’t agree to was putting their name on the coffee shop that gets destroyed. (source)

10 In the cave scene, the visible breath might be a recycled version of Leonardo DiCaprio’s breath from Titanic.

There’s a scene in the movie where the narrator goes into a cave and tries to kiss Marla who blows smoke into his mouth. Also in that scene, there’s a lot of icy breaths from the narrator. It is believed by many that there’s a chance the narrator’s breath might belong to Leonardo DiCaprio from the movie Titanic.  What led people to believe this was that Blue Sky Studios, the company responsible for CGI effects in the movie, had past associations with VIFX, the company that worked on Titanic. VIFX has earlier quoted that they have a “library of generic breath elements created for Titanic” to be used for further projects.

Moreover, in an interview, John Siczewicz, digital artist for Fight Club,  is quoted as saying: “After starting with those existing breath elements (from Titanic) we cut and pasted and dissolved until we had some animated breath that worked with the wind action within this ice tunnel. Since either the camera or the actor was in motion for all of these shots, I had to track in the origin point for each breath. Once these swirly breaths blended in, the whole scene dropped sixty degrees.”(source)

11 After the narrator meets Tyler, he calls him from a pay phone. Tyler doesn’t answer but calls back. The camera zooms in to show the payphone which has a message that “no incoming calls allowed,” thus offering a subtle hint that Tyler isn’t real.

This is a subtle clue at the beginning of the movie that Tyler isn’t real. After the narrator’s condo blows up and burns to the ground, he calls up Tyler. He calls from a payphone just outside his condo. But Tyler doesn’t pick up at that time. A few seconds later, the narrator gets a call back from Tyler on the same pay phone. As the phone rings and the narrator goes forward to answer it, the camera zooms in on a sentence written on the payphone. The sentence is “No incoming calls accepted.” This means that it would be impossible for the narrator to have received that call from Tyler, and hence, Tyler is not real! If you have missed this the first time you watched the movie, go ahead and watch it again!

That is not the only clue that the movie offers. In another scene where the narrator and Tyler both get on the bus, there is another subtle clue. A long-haired guy enters the bus and walks past both of them. When he walks past Tyler, he just pushes ahead without any word. But when he pushes past the narrator, he says “excuse me.” This is another hint that most of us miss the first few times we watch Fight Club hinting to us that Tyler Durden is not real. (1,2)

12 Marla Singer’s phone number is same as the phone number of Teddy in the movie Memento. It is also same to the phone number of the Hong Kong Restaurant in Harriet The Spy, the phone number of Eddie Alden in the movie Someone Like You, and also the phone number for a mental institution in one of the episodes of Millenium.

Looks like the number has been used quite a lot in Hollywood! (source)

13 Brad Pitt’s reaction “He hit me in the ear!” was genuine. Ed Norton was scripted to fake hit him, but the director secretly changed it at the last moment.

In the scene when Tyler Durden asks the narrator to hit him, he actually hit him hard. In the original script, the narrator was supposed to fake hit Tyler on the shoulder. But just before the scene was shot, director David Fincher summoned Ed Norton to the side and told him, “Hit him a bit harder than he’s expecting.” Norton obliged and hit Brad Pitt hard and on the ear. Brad Pitt had no idea this was going to happen, and his reaction  “He hit me in the ear!” was entirely genuine. (source)

14 In the “pillow talk” scene, Marla’s line, “I haven’t been f*ck*d like that since grade school” was originally supposed to be “I want to have your abortion.”

After Tyler and Marla had sex, she says to him, “I haven’t been f*ck*d like that since grade school.” This line was originally supposed to be “I want to have your abortion.” What happened was Fox studio executive Laura Ziskin was appalled by the abortion line. She asked the director, David Fincher, to change it to something more acceptable and appropriate.

Fincher agreed to this but made a pact with Laura that he will change the line only on one condition – that it will not get changed again. Laura agreed to it as she didn’t imagine that the line could get any worse. But Fincher came up with an equally controversial and appealing line and Laura couldn’t do anything as she had to honor the pact made with Fincher. (source)

15 Bob’s fat suit weighed more than 100 pounds. Moreover, to make the sagging flesh look more convincing, the suit was filled with birdseed.

That’s true! To play the part of Robert “Big Bob” Paulson, Meat Loaf had to wear a 100-pound fat suit. The suit was filled with rice and birdseed so that the sagging flesh would look more real. The suit also featured two breasts that wobbled convincingly under Bob’s t-shirt. (source)

16 While giving a speech at one of the Fight Club meetings, Tyler looks directly at Jared Leto’s character when he mentions rockstars. Jared Leto is the founder of the now platinum-selling band 30 Seconds To Mars. 

In a scene, Tyler gives an inspirational speech to the people present at one of the Fight Club meetings. He says, “We’ve all been raised on television to believe that one day we’d all be millionaires, and movie gods, and rock stars.”

When he says the line about rockstars, he looks directly at the character played by Jared Leto. Just one year prior to the release of Fight Club, Jared Leto founded the now famous band 30 Seconds To Mars. (source)