When Kat is drunk, and her and Patrick are walking up the hill, after she starts crawling, Heath Ledger calls her "Kate". This could be a reference to "Taming of the Shrew" and "Kiss Me, Kate", when Petruchio intentionally calls Kat "Kate", a nickname Katerina hates.
As Michael makes his way to Mandella at the prom, you see Patrick and Kat spin away in the background. In the next shot, they are still standing there behind Mandella watching Michael approach. In the next shot, they are gone again.
In the scene where Bianca and Cameron are under a bridge and he's asking her does she like sailing, in one shot she has roots in her hair about an inch thick and in the next she has none, her hair has been dyed.
When Cameron first approaches Patrick about dating Kat, he responds by drilling a hole in Cameron's French book. But when Michael holds up the book in the next scene, the hole is far larger than the drill bit Patrick was using would have made.
When Kat and Patrick are on the porch, Kat asks Patrick to tell her something true. When she says this there is a strand of red paint-stained hair on the side of her face. When Patrick kisses her neck, the hair is tucked neatly behind her ear.
During Patrick and Kat's first conversation, they pass a bench at the side of the field. The scene cuts to Cameron and Michael in the bleachers and Patrick's position has changed. There are also many more people near the bench than in the previous shot.
When Kat want to back out of the parking spot Joey parks his car behind her. The door of his car is completely visible. But when Kat purposely backs up into Joey's car she hits it with the right rear corner in the middle of the door, as seen in the close-up. That is only possible if Joey's car would have been parked a further four to five feet to the front.
When the microphone is turned on for the song and the sound board is shown, a feedback sound effect is heard although the sound board shows quite clearly that the microphone is turned off at the sound board.
Right after Joey says, "OK, you're cool by association," when he's done drawing on Michael's face, an arm and short sleeve shirt are visible above Michael's head on the left side as if someone is standing by the table. In the next shot when it shows the whole table, no one is near their table.
The poem that Kat reads in Mr. Morgan's English class towards the end of the film is titled "10 Things I Hate About You". It uses the word "hate" exactly 11 times and actually lists 13 disliked qualities.
Bianca announces she is the only Sophomore invited to the prom. Instead of going to the prom with Joey, she goes with Cameron. Bianca runs into her best friend, Chastity (also a Sophomore) at the prom, who announces Joey picked her up for the prom. Some think Chastity could never get a prom dress on such short notice. However, there are many possibilities: Chastity could have an older sister with a dress that also fits Chastity; Chastity could compete in pageants and have gowns on hand; Chastity could borrow a dress from her Mom (some women do attend formal events and own gowns for them), or a neighbor might have had a gown.
In the scene in which the teacher gets an arrow fired into his backside by Bianca, a girl runs off to go find help, however before she runs off camera she stops and looks back, obviously unaware she is still on camera.