Trivia: In the scene where Mia slips and falls on the bleachers, Anne Hathaway actually did fall. The director thought it was so funny that he decided to leave it in there. Notice how Mia and Lilly fall out of character and start laughing, but in the next shot they're immediately serious again as if nothing happened.
Trivia: During the first formal dinner that Princess Mia attends, when she taps on her glass to get everyone's attention, and the glass breaks, take note of the waiter who attends to the broken glass and says, "Don't worry, it happens all the time." The actor, Alan Kent, says the same line in Pretty Woman during the famous "slippery snail" incident. Both films were directed by Garry Marshall.
Trivia: Michael Moscovitz in the movie, the guy who likes Mia, plays in a band in one part where Mia goes to visit her "baby". The actor is Robert Schwartzman, now known as Robert Carmine in honor of one of his relatives. He is the lead singer in the band "Rooney" and when his band plays at the mechanic's in the movie, it is actually part of the song "Blueside" by Rooney. Also, actor Jason Schwartzman is his brother, and his cousins are Sophia Coppola and Nicolas Cage.
Trivia: In the scene where Heather and Anne are first in the limo together, there is a shot shown of what appears to be Lily's hand, which has a number of rings on, touching switches in the limousine. In all actuality, that is Anne's cousin's hand we see. She also has a cameo role in the film. In the scene where Robert's band is playing in the garage, she's the fair-haired girl next to the girl who speaks about one of the band members.