Artistic License – Music: Despite being told to play side one of "Led Zeppelin IV" on his date, Mark ends up playing Kashmir from "Physical Graffiti" instead. This is partly Genius Bonus (few outside of the truly devoted would know exact Zeppelin track listings) and partly Throw It In. The producers were unable to secure clearances for "IV" and it could be played off as Mark picking the wrong album.
Dawson Casting: Phoebe Cates was 18 when she appeared in this film, and she was the youngest actor in the main cast.
I Am Not Spock: Sean Penn would rather not be associated with Spicoli nowadays.
Subverted with Ray Walston. For a long time after the film was released, people frequently addressed him as Mr. Hand. Walston was very grateful for this because up until that time, he felt that he was too closely associated with his prior role of Uncle Martin in My Favorite Martian.
Recycled: The Series/Spin-Off: Fast Times, a series that aired for only seven episodes in 1986 on CBS. Produced by Amy Heckerling and with Cameron Crowe as creative consultant, only Vincent Schiavelli (Mr. Vargas) and Ray Walston (Mr. Hand) reprised their roles from the film, though it's also notable for being Patrick Dempsey's first television role.
The Red Stapler: Sales of Vans shoes increased following the release of the movie, where Jeff Spicoli wore his Vans black-and-white checkerboard slip-on shoes.
Sleeper Hit: Universal originally planned to only release the film in the Western part of the United States for a few weeks before sending it off to cable (regional releases were still common at this time) due to the belief that there was no audience for it. After an excellent response, the film went wide three weeks later with a big opening in the Eastern United States and had a long run in theaters.
Throw It In: The scene where Spicoli is interviewed by Stu Nahan and utters the immortal line, "Hey bud, let's party!" was a last-minute addition to the movie after plans to film Spicoli singing "Highway to Hell" fell through (see What Could Have Been below).
What Could Have Been: The studio originally considered Nicolas Cage for the role of Brad, but after his audition, Amy Heckerling thought his performance was too dark and instead offered the role to Judge Reinhold. Additionally, Cage was 17 at the time, and thus he could not work as many hours as those for actors 18 and over. In addition, Fred Gwynne was originally offered the role of Mr. Hand, but he turned it down because he felt that the sex scenes involving Jennifer Jason Leigh were too objectionable.
In the novel, Spicoli dreams he's singing "Highway to Hell" on The Tonight Show (with Johnny Carson hosting), but Carson refused to do it for the movie, and other talk show hosts (including David Letterman) also turned it down (Letterman apparently was willing to do it, but his agent wouldn't let him appear in a movie where the characters did drugs). In its place was the scene where Spicoli is interviewed by sports announcer Stu Nahan.