In the scene where the princess is leaving the castle to dance , it clearly begins during the night, but when she steps outside and walks to the carriage it is daytime, and when she arrives at her destination, it is yet again night.
During The Dancing Princess, on the return trip to the castle the carriage crosses a dilapidated wooden bridge that is not only too narrow for the two-horse drawn carriage but also has many missing boards. The horses hooves would have come down on large empty holes, causing the horses to either break their legs or smash and fall through the boards. At the very least, they simply couldn't have crossed that bridge.
Automobile visible driving in the distance when the brothers are walking along the street.
The Dancing Princess is set during a rather fancifully depicted Middle Ages. However, the royal palace in which she lives is the Castle Neuschwanstein, which was not built until 1869-1892. Contemporary visitors are surprised to learn that the castle is not ancient, having had running water and primitive electric lights and telephones. However, the actual youthfulness of the castle is not visually apparent. because it was designed to look like a medieval fairy tale castle.