About 5 minutes before the end of the movie, when Max rides up to the City Hall, Allie stands up from leaning on the balustrade. In the next shot, as Max stops his horse, she is leaning on the balustrade again and stands up again.
The King is frequently addressed as "Your Highness" as a King he should be addressed as "Your Majesty". As a princess Theodora would be addressed as "Your Highness"
When Allie calls her sister, it is Christmas Eve afternoon (light outside) in Europe but Christmas Eve night in New York city where it would have been 4 or 5 hours earlier.
Near the end of the movie Allie hands over a carrier bag containing pencil sketches of the palace staff, when they open them they are in large presentation boxes, there is no way they would all fit in a small carrier bag.
Theodora tells Miss Evans not to hold onto the saddle horn when riding. Those saddles did not have saddle horns.
At about the 26 minute mark of watching on television and not DVD, there's a glitch in the green screen used and you can see that the nightstand lamp duplicates and looks like 2 lamps appear on her nightstand in her bedroom.
When princess Celia says that they'll get married in the spring, Theodora
says what spring where she says this years spring. Well that can't happen as Spring had already passed and it was now winter soon to be Christmas, so she should've said spring next year.
There is no Pullman Hotel at NYC.
When Allie is introduced to the staff upon her arrival at the palace, she is reprimanded by Miss Wick for using a first name and informed that they "use formalities" there. Miss Wick then immediately calls Carter by his first name rather than using his formal title, thereby breaking her just mentioned requirement to use formalities.