1. The shot of Vincent plunging the syringe into Mia's chest was filmed by having John Travolta pull the needle out, then reversing it.
2. Mia and Marsullus Wallace never speak to one another in the film.
3. The contents of the briefcase are meant to be a mystery.
4. The diner scene was shot at Hawthorne Grill in Hawthorne California. It has since been demolished.
5. Something bad happens each time Vincent Vega goes to the bathroom.
6. Jackson's character was originally supposed to have an afro, but after Jackson tried on a jheri curl Tarantino liked it so much he kept it.
7. Matt Dillion and Sylvester Stallone were considered for the role of Butch.
8. The bandage on the back of Masullus' neck has no significance whatsoever.
9. Alfre Woodard, Annabella Sciorra, and Halle Berry all auditioned for the role of Mia Wallace.
10. Uma Thurman initially turned down the role of Mia Wallace.
11. Bruce Willis was only on set for 18 days.
12. The word "fuck" and its derivatives are used 265 times.
13. The passage from the Bible that Jules has memorized was mostly made up. It was originally written for Tarantino's film From Dusk Till Dawn.
14. John Travolta took over a dozen tequila shots and sat in a warm pool to simulate a heroin high.
15. Vincent's Chevelle Malibu actually belonged to Tarantino and was stolen during the filming of the movie.
16. The famous BMF wallet actually belonged to Tarantino, and was a homage to the Shaft movies of the 70's.
17. Rachel (Julia Sweeny) was married to the Gimp (Stephen Hibbert) in real life.
18. A quarter pounder is not called a "Royale" with cheese anywhere in the world.
19. Pam Grier was considered for the role of Jody, Lance's wife.
20. The iconic dance scene was actually an homage to a scene in Federico Fellini's 8 1/2
All facts curtesy of IMDB.