The 10th Kingdom (2000)

Prince Wendell's coronation is cancelled due to his absence, as unbeknownst to his kingdom, he is still trapped as a dog and traveling with Virginia and Tony Lewis. To their horror, the imposter Prince Wendell arrives to be crowned king and the forces of the Evil Queen chase the true Wendell deep into the wilderness. Even worse, the magic mirror needed to return to New York has shattered.