Deliberate mistake: When the Creeper gets stabbed through the eye with the javelin, it goes through the front of his eye, but when it comes out the other end the eye is facing backward. (00:50:00)
Deliberate mistake: There is one scene in the movie where Heath Ledger reads a Latin sentence in a book. As he is translating the sentence, he goes over the words one by one with his finger. This would never be possible in a Latin sentence, because words in Latin are never in exactly the same order as in English. Words that actually belong together can be placed at opposite ends of a sentence.
Deliberate mistake: When Leota is in the front seat of the automobile, the air bag is still full. Air bags will deploy and then immediately deflate to prevent people (or women in crystal balls) from being trapped. (01:10:45)
Deliberate mistake: When the teacher walks over the floor towards the blackboard, he walks through a lot of blood. However when it cuts, he leaves no traces of blood where he steps.
Deliberate mistake: When Kimberly is being revived, it's obvious that they are using a defibulator. But when Kimberly finally comes to and is covered by a sheet, you can see she has a bra on. This is impossible to have because you need direct contact with the skin in order for it to work. And the machine would start the heart working if it was lower on her chest.
Deliberate mistake: When Kyle goes through the windshield, the windshield shatters like tempered glass. Windshields at the time were made of laminated glass.