The animated film is an adaptation of not specifically the original fairy tale by Selma Lagerlöf, but her retelling by Zoya Zadunayskaya and Aleksandra Lyubarskaya in 1940. But even in comparison with the retelling, the plot of the animation is significantly shortened.
The film was restored at the Gorky film studio in 1988.
In the original text of the book the goose is called Morten, and in the retelling (as in the film) - Martin.
In the film, Niels himself makes a pipe that fascinates the rats. In the retelling of the book it lends him a gnome, and in the original - the old owl.
To enhance the image, the artists gave the leader of the hordes of rats the features (bangs on the head) and the behavior of Adolf Hitler.