1.In Clueless, after Tai bumps her head, Elton asks if she can dance and sing the lyric "rollin' with the homies." This lyric is incorrect. It's actually "rollin' with MY homies," from Coolio's hit single.
2.In A Cinderella Story, Brianna and Gabriella are always seen wearing pink and green, much like the evil stepsisters from the 1950 Cinderella.
3.In Easy A, the foreign film Olive goes to see is the German language version of The Scarlet Letter, which is the book the movie is based off of.
5.In Mean Girls, Gretchen tells Cady that she's not allowed to wear hoop earrings because they're "Regina's thing." Towards the end of the movie, we see Cady wearing hoop earrings when she takes over the plastics, thus solidifying her as the new Regina.
6.Also in Mean Girls, at the end, when The Plastics fully disbanded, Gretchen was finally able to wear her hoop earrings.
7.In The Breakfast Club, the license plate of the car Brian (the brain) gets out of reads EMC2 (E=MC^2). The license plate of the car Andrew (the jock) gets out of reads OHIOST (Ohio State).
8.In Ferris Bueller's Day Off, we see a poster that says, "Go Shermer," which is the high school in The Breakfast Club, proving that both of these movies take place at the same school.
9.In 10 Things I Hate About You, Nigel with the brie is the first one through the door after the teens of Padua High crash Bogey's party.
10.In Heathers, when JD was explaining to Veronica that the bullets were blanks, he calls them "Ich Luge" bullets, which, in German, means "I'm lying." This is why he asked Veronica if she spoke German.
11.In Sixteen Candles, the numbers on the license plate of Jake's car add up to 16.
13.In Princess Diaries, after Mia gets outted as a princess and all the reporters swarm her school, you can see one reporter in shorts and sandals because he only needs to be presentable from the waist up.
14.In Princess Diaries 2: Royal Engagement, Stan Lee makes a rare non-Marvel cameo.
15.In Never Been Kissed, when Josie becomes popular, the other popular girls begin wearing pilot pins, too. (Josie wore hers because it was actually a camera to record the inner going ons of the school.)