When Josh is hit with the softball, the ball bounces out of sight. In several consecutive shots, the ball is nowhere around him. However, when another boy yells at him to "pick it up", the ball suddenly appears next to him, and he throws it home.
Before Mia slides down the firepole during the opening scene she is wearing glasses. When she gets to the bottom of the pole she isn't wearing them then when she walks across the room to leave she has them on again.
At the state dinner, Clarisse asks Emperor Sakamoto if he wants to look at some pictures. He says no and takes a sip from a spoon of what appears to be soup. However, the soup hasn't been served yet.
During the state dinner scene, when Mia drops a grape on the floor it can clearly be seen as green, but when she bends down to pick it up, it has changed to a red grape.
When Mia is sitting with Jeremiah, Lana says, "Sunglasses girls!" and she and the other two put on glasses. But when Lana stands up and faces Mia, her glasses are gone.
In the state dinner scene, Mia is seated next to Prime Minister Motaz, who can be seen wearing 3 military medals. The medals in the middle and on the left (closest to his left arm) are the British War Medal and the British Victory Medal from WW1. Those were issued to veterans of the First World War (1914-1918). Given the PM's age, he would not have served in WWI and been awarded those medals.
The royal limo is seen to pull up outside the school but then in a slightly longer shot as the queen (Julie Andrews) gets out it's seen that it's parked so close to a school bus that it wouldn't have been able to pull in.
Prior to Mia breaking the finger from the Genovian statue, the seam in the finger can be plainly seen.
When it is raining and Mia uncovers her Mustang, the car is already wet, possibly from previous takes.
When Mia smeared ice cream on Lana's cheerleader dress, most of the students chant "Lana got coned!" very loudly. But in the next shot, they aren't chanting. Instead, they're only spectating Lana getting humiliated. And suddenly, when Lana was whining at Mrs. Gupta if she witnesses what Mia did to her dress, the students are chanting again.
When we first see Michael at the auto shop he's practicing with his band. They show two girls watching the band. One of the girls says, "He fixes cars, he plays guitar... and he can sing -He is so hot! -He is wicked sweet. ". While she is saying this the camera is set on Michael, who is playing the keyboard, not the guitar which indicates she is not talking about Michael but the guitar player who can be seen talking to the girls later in the scene.
When Mia is driving the Mustang up hills with her grandmother, it is implied that it is a manual because it keeps drifting backwards on hills (it even drifts all the way down a hill and hits a bus). Also there is a close-up shot of her putting both feet on the brake pedal. Later in the movie when she's driving to the ball in the rain, the car stalls and she lays down on the front passenger seat. You can clearly see the gear shifter and it is an automatic. Therefore it wouldn't drift backwards on hills.
On the school roof Mia is shooting basketball one handed while holding an umbrella in her other hand and is being watched by Joe who also has an umbrella up. The ground is wet but only in one shot is it actually raining.Mia finishes shooting baskets and sits on a bench and suddenly her brolly is folded up.
After Mia breaks the glass for the speech during the State Dinner, she picks up her neighbor's (on her right) brandy glass and raises it for toasts.
The TV reporter Nelson Davenport says that Mia is Clarisse's only grandchild. However, in an earlier scene, Clarisse says that Mia has a cousin named Bartholomew. This would make Bartholomew her grandchild too.
At the beach party, when Lana and her two friends get on the stage to sing, neither one of the friends' mouths move at all, although backup singers are clearly heard.
When the vice-principal says, "Oh, come on, girls, it's a ball, not a snake," her mouth doesn't match the words.
On the way to Musée Méchanique, we see Mia and her grandmother driving over the Golden Gate Bridge toward Marin County. However, Musée Méchanique is located in San Francisco.
On the way to Musée Méchanique, after the trip in the wrong direction on the Golden Gate Bridge, the next shot the car is driving south on the Great Highway, between Balboa St. & Fulton St. At the time the movie was shot (2000) the Musée was located at the Cliff House, north of that location.
Helen tells Mia that they (the Queen, Mia's dad and Helen) were planning on telling Mia about her heritage when she turned 18. However the letter from Mia's dad was for her 16th birthday and it has the royal insignia on the letter head. Wouldn't that give it away?
When Paolo sets out to brush Mia's hair, he orders his assistant "Helga" to hand him the brush in make-believe German. He says, "Brüste, Helga," which translates as, "Breasts, Helga." The correct word for "brush" in German is "Bürste".
When Clarisse is first introduced, she is crossing her legs. But, in the princess lessons scene, she tells Mia that royalty never cross their legs, only their ankles.
The Genovian motto written in Latin "Totus Corpus Laborat" has a grammatical error in it. The motto should actually be "Totum Corpus Laborat". Totus is a masculine form of the adjective, but the noun corpus is neuter.
When Queen Clarice and Mia are talking to the police after Mia hits the trolley car, the queen tries to claim diplomatic immunity as a way to get out of the ticket for the accident, which the officer promptly denies, as Mia is not subject to immunity. However, traffic tickets have never been included in offenses excused for diplomatic immunity. Thus, even if immunity had applied to Mia, she still would have gotten a ticket.
At their second meeting, Clarisse tells Mia to wear "stockings, not tights" on her next visit. However, the garment that Mia is putting on in the back seat of the limousine, en route to the consulate the next day, is a pair of tights, not a pair of stockings, as the queen specified.