Question: How is Emma sitting on the horse and cart when she is lighter than air? I have watched the movie a few times and cannot see anything like a belt around her waist, but any other time she is sitting, she has been seen buckled down.
Answer: This is a movie mistake because when she's at dinner, she has to wear a buckle to hold her down. And I don't see why she wouldn't be wearing one on the carriage too.
Chosen answer: At several points throughout the film, there are instances where her powers of air are used only as a plot device, so the extent of her powers is somewhat unknown. Therefore, it is possible she is able to make herself sit on the cart without floating, but other times isn't.
Amina Thommesen-Kähler