Night on Bald Mountain, Walt Disney’s animated rendition of Modest Musorgskij’s Ivanova noč’ na Lysoj gore, follows the structure of the work, linking the main theme to the demonic figure of Černobog and introducing new ghostly or monstrous creatures for each new musical section.
The climactic orgy includes all of the previously introduced characters as well as newly introduced ones, often depicted in an expressionist style that contrasts with Musorgskij’s own realist aesthetic—indeed, expressionism was an overt rebellion against realism’s Romantic ideals.
Disney’s version also follows the program of Musorgskij’s work as the village church bells put a stop to the hellish festivities, but a happy ending was deemed necessary, resulting in an unfortunate segue into an inappropriately Romanticized arrangement of Schubert’s Ave Maria.
This according to “Klasična glazba u crtanom filmu <Fantazija> (1940.) Walta Disneya” by Irena Paulus (Arti musices: Hrvatski muzikološki zbornik XXVIII/1–2  pp. 115–27).
Today is Musorgskij’s 180th birthday! Below, the full segment from Disney’s Fantasia.