Most of these were found here, or here
1. The actress who played Moaning Myrtle was 37 years old at the time “Harry Potter and the Chamber of Secrets” was filmed. She is the oldest actress to ever portray a Hogwarts student
2. Only Alan Rickman, the actor who played Professor Snape, knew his character’s fate before the release of “Harry Potter and the Deathly Hallows” because Rowling told him.
3.An outbreak of lice occurred among the children cast members during the filming of “Harry Potter and the Chamber of Secrets.”
4. The idea for Sirius Black’s tattoos came from those used in Russian prison gangs. The markings identify the person as someone to be feared and respected.
5. During the filming of the kissing scene between the horcrux versions of Harry and Hermione in the final film, Rupert Grint was removed from the set for laughing too much.
6. In order to become acquainted with the films’ three main stars, director Alfonso Cuaron had each of them write an essay about their characters. True to their characters, Emma Watson wrote a 16-page essay, Daniel Radcliffe wrote a simple, one-page paper, and Rupert Grint never even turned his in.
7. A picture of Gandalf the Grey (from The Lord of the Rings) can be seen in the collection of great wizards in Professor Dumbledore’s study in Harry Potter and the Chamber of Secrets
8. Rowling said that if she were to be a teacher at Hogwarts, she would teach Charms. If she had a job in the wizarding world, she would write spell books
9. Colors play an important role in the Harry Potter novels. For example, shades of red represent goodness, such as Gryffindor’s scarlet robes, Harry’s red ink, and the crimson Hogwarts Express train. The Weasleys have red hair and a red roof. Green is largely associated with negative events, such as when Harry sees a flash of green when his parents die and the green-colored curse that made Ron vomit.
10. So many fans visit King’s Cross station to take pictures of platforms 9 and 10 that the station management erected a sign that says “Platform 9 ¾” which, in the Potter books, is invisible to Muggles but acts as a gateway for witches and wizards
This last one is true and I have a pics somewhere to prove it LOL
Okay there are 10 facts about Harry Potter for you... stayed tune for more HP stuff this week.