Actor Allusion: In the Season 6 episode of "Dear Apple" has Jo mentioning a series of incidents to a computerized advice program as part of her questioning whether she should remain friends with Blair; including an incident where Blair (pretending to take a really long shower {thus letting the water run cold; something Jo finds out when Blair exits the bathroom}) while singing "Zip-A-Dee-Doo-Dah"; clearly referencing Lisa Whelchel getting her start on the 1970s New Mickey Mouse Club.
I Am Not Spock: Nancy McKeon didn't come back for the reunion, in part because of her commitment to The Division, and in part because she didn't want to be Typecast as Jo anymore.
John Astin (of The Addams Family fame) guest-starred in the sixth season premiere as Edna's love interest. Coincidentally, his son Mackenzie would join the cast in later seasons as Andy Moffett.
Recycled Script: Both episodes involving Flyman, "Gone with the Wind" and "Atlantic City", use the exact same plot for Tootie. In both episodes, Tootie tries to pass for 21 in an over-21 establishment (a bar in one, a casino in the other), tries too hard to seem grown-up (pretending to be a cast member from Fame in one, pretending to be a rich socialite in the other), and tries to hook-up with a boy who is also trying too hard to appear older than he actually is.
Typecasting: During the college episodes, Jami Gertz pretty much plays the exact same character she played in Square Pegs. Both characters were even given silly rich girl names, Muffy in Square Pegs and Boots in Facts.
Molly Ringwaldrevealed in an interview that she was originally supposed to stay on as a regular for season 2. However, the producers decided that they needed an older girl who could be a Foil for Blair, so they dropped Molly and created Jo. The experience of being hired and then fired was so disappointing to Ringwald that, after one scene in the season 2 premiere, she turned down offers to do guest appearances on the show even before she became a movie star.
In one making-of special, the girls mentioned how, in the episode "The First Time," the writers initially had the idea of Blair losing her virginity. Lisa Whelchel objected on religious grounds, and in fact doesn't appear in the episode at all, so the story was given to Natalie instead.
Written-In Infirmity: Nancy McKeon had broken her foot shooting the Made-for-TV MovieStrange Voices shortly before shooting for the final season began; thus resulting in her foot being in a cast for a few earlier episodes that season.
You Look Familiar: Todd Williams, the actor who plays Tootie's long-term, late-series boyfriend Jeff, makes an early appearance as Zack, a Bates student who goes on a camping trip with the group. Actor Thomas Byrd also appears twice in the series both times as love interests of Blair.