3. The original script was called The Princess of Tribeca and it was set in New York like the books, not San Francisco.
6. Despite not having time to do a screen test, Hathaway was cast on the basis of that audition.
7. During her audition Hathaway was asked to do a French accent, and at one point accidentally fell off her chair.
8. Meg Cabot said she was inspired to write the story because of her own life experiences: "I was inspired to write The Princess Diaries when my mom, after the death of my father, began dating one of my teachers, just as Mia's mom does in the book!"
9. Mia's father was not dead in the books and instead has testicular cancer, a plot which was not included in the movie.
10. The man who appears as Mia's father in a flashback writing a letter, and in the photograph on her shelf, was actually Anne Hathaway's father.
11. Robert Schwartzman, who played Michael, is actually in a band called Rooney. Two of his real band members acted in the film as part of his band Fly Paper.
12. Hathaway had to wear a wig and fake eyebrows to play the character of Mia.
14. During filming Hathaway went out in public as Mia and said of it, "I've never felt so alone in my entire life."
16. When Mia breaks a glass at the fancy dinner, a waiter says, "It happens all the time." That waiter is played by Alan Kent, who says the same line in Pretty Woman, after the escargot incident.
17. Larry Miller, who played Paolo, and Héctor Elizondo, who played Joe, both also starred in Pretty Woman.
18. Elizondo has appeared in all the films that Marshall has directed.
21. The pier where Mia and Queen Clarisse play arcade games is the Musee Mecanique, a collection of vintage mechanical amusements on Pier 45 in San Francisco.
22. This movie was filmed on Stage 2 in Walt Disney Studios in Burbank, California, the same stage where Mary Poppins was filmed.
23. The house that Julie Andrews lived in while filming Mary Poppins is owned by Garry Marshall.
24. The converted San Francisco fire station that Mia and her mother live in that was used for exterior shots was sold for $1,850,000 in 2015.
25. The interior shots were filmed in a studio where the set was built to match the exterior layout of the house.
26. In the movie, Genovia is located between France and Spain, similar to real-life Andorra.
27. The Genovian Consulate where Queen Clarisse stays is not in fact a building in San Francisco, but was filmed at Mount Saint Mary's University in Los Angeles.
28. The Baker Beach party scene was filmed in Malibu, rather than San Francisco.
29. San Francisco Mayor Willie Brown portrayed himself in a scene at the Genovian embassy, where he was interviewed upon his arrival at the Genovian ball.
30. Director Marshall's wife Barbara also had a cameo at the Genovian ball.
31. The Latin motto on the Genovian crest, "Totus Corpus Laborat" is improper. It should read "Totum Corpus Laborat", meaning "The whole body works."
32. And of course, sadly, Genovia is not a real country.