You remember your U.S. History, don't you? Butch's fight—Coolidge vs. Wilson—is a reference to the presidents Calvin Coolidge and Woodrow Wilson (even though they never ran against each other). We can hear Warren Harding asking, "so what am I, chopped liver?" The other featured fight is a reference to two of Tarantino's friends from his old video store days, Jerry Martinez and Russell Vossler. (Source)

How did John Travolta appear to be plunging a hypodermic needle into Uma Thurman? Tarantino filmed him removing the needle then ran the film backwards. (Source)

For the scene when when Mia is drooling from her moth after the overdose, the crew used Campbell's Cream of Mushroom soup. Mmm-mmm good. (Source)

The scene where Marsellus stops directly in front of Butch's car and turns to look at him is a shout-out to a very similar scene in the famous Hitchcock movie, Psycho. (Source)

To prepare for his role as a heroin addict, Travolta spoke with an addict about how to play a heroin high. The addict suggested he get drunk on Tequila and lie in a hot tub. Do not try this at home. (Source)

Samuel L. Jackson was supposed to wear a huge Afro wig in the film. But when a production assistant brought back a Jheri-curl wig, Samuel L jumped on it because he said that's what all the gangbangers were wearing. Travolta convinced Tarantino to let him use hair extensions to get that "Eurotrash" look. (Source)