In the beginning of the film, Chili mentions how a film needs to only use the "F" word more than once in order to get an R rating. He then uses the "F" word - the only use of it in the film - and thus, it gets a PG-13 rating.
Elmore Leonard named Dwayne Johnson's character after real-life film critic and Detroit Institute of Arts film curator Elliot Wilhelm (the real Wilhelm makes an uncredited appearance early in the film as a patron at the Viper Room).
When Sin LaSalle goes to call Raji after the threatening "prank" call, we get to see two of the numbers in Sin's cell phone directory. One is R. Lowenthal (Raji), the other is G. Gray - an obvious reference to director F. Gary Gray.
This is the last movie where Dwayne Johnson is shown in credits as "The Rock". He would be credited as Dwayne "The Rock" Johnson after this movie and he would drop "The Rock" and just go by Dwayne Johnson. Only in WWE productions is he referred to as "The Rock".
The scenes at the NBA game with John Travolta and Uma Thurman were filmed at the Staples Center during a game between the Lakers and the Sacramento Kings on 26 February 2004. Although the film depicts the Lakers winning the game, they lost 101-103.
In the scene when Elliot (Dwayne Johnson) is chasing Raji (Vince Vaughn) around the car, most of the scene was improvised. At the end, when Raji was saying, "E. Weasy" and started to dance, once the camera moves back, you can see Elliot smiling.
The infamous monologue that Sin LaSalle delivered was neither in the novel nor in the early drafts of the script. The idea was put on by director F. Gary Gray who wanted Sin to be likable, but serious at the same time as well.
At one point in the movie, Raj is referred to as "Vanilla Ice". In hip-hop folklore, it's said Marion 'Suge' Knight took Vanilla Ice out to a balcony of a hotel and dangled him over the side by his ankles. Raj went through the same scenario.
The trivia item below may give away important plot points.
Even though the film clearly deviates from the novel, there were some moments in the film which serves as a nod to the source novel: 1) The burn-out photo that Tiffany has (later picked up by Chili) is a nod to the fact that in the novel, the Russians operate a one-hour photo shop instead of the pawn shop. 2) The confrontation between DubMDs and the Russians in Nick's office is a nod to the intended shoot-out between the two. In the novel, neither parties appear in the second half. 3) When Raji tries to setup Sin LaSalle against Nick, Raji deliberately spell Carr's last name as CAR. In the novel, Nick's full last name is Carcaterra.