When Ottilie dreams herself in the clouds she sees Otto Siedler far away flying. In the next shot from another angle he is right in front of her.
When Ottilie and Sigismund are jumping from the cliff with their parachutes he's jumping on her left side holding her hand. In the next shot after the jump he's flying on right side, holding her right arm.
When the double rainbow appears, the order of the colors of the secondary (outer) rainbow is the same as in the primary, in fact it should be reversed. Additinally the shadows cast by objects or persons should point to the center of the rainbow, Otto's shadow is once seen pointing perpendicular to the direction in which the rainbow is seen.
Many plot holes in the story, which were added for the movie. However this could have been intentionally, as the White Horse Inn is symbolized as a different world and this can be considered as a pun or parody to the old Schlagermovies.
When Ottilie first arrives in Salzkammergut and hears the children choir is singing, most of the children don't move their mouth, while their singing can be heard.
In the movie it is said that everyone is singing. However in the opening number at the White Horse Inn some characters don't move their mouths, even if singing is heard.
When Sigismund Sülzheimer dances at the Alm, a flag of the Austrian state Salzburg is hanging in the wind. Very unlikely for an Alm, which supposed to be in Salzkammergut, a region in the neighbor state Higher Austria, where the movie is set.
How did Leopold get Sigismund's employer documents in the first place, since he was fired and should not have access to this? Did his former colleague, the cook, gave it to him? Did he stay as a guest in the hotel, as in the original play? Did he even sneak into the hotel?
How does Ottilie know, that they will meet Sigismund at the Shoeplattler-championship? He wasn't announced for that.
Leopold pointed to a photo in Sigismunds employee documents on page two but when Dr. Siedler is reading the documents they are on page four.
Josephas full name is Maria Gabriella Josepha Voglhuber, just as in the original play. However when he signs the selling contract of the White Horse Inn her name is called Josepha Magdalena Voglhuber.