The use of Esperanto in cinema has been discussed, for example: Esperanto and Cinema. One example, which has been documented in various places, is the film Idiot's Delight. (The Esperanto version of the Wikipedia article does not give an adequate explanation for the use of Esperanto in the film). In a recent historical work, the political context is outlined:
Throughout
the film industry's relatively brief existence, moviemakers—protective of their
profits and worried about private pressure groups and government censorship—had
done their best to avoid controversy. They were particularly concerned about
not offending important foreign markets, which accounted for at least half
their annual revenues. In the 1930s, Germany and Italy were key outlets
for American movies, and studio heads were reluctant to do anything that might
anger those countries' totalitarian leaders.
Robert
Sherwood was made aware of that fact when his Pulitzer Prize-winning play, Idiot's
Delight, was optioned by Metro-Goldwyn-Mayer in 1936. Both
antiwar and anti-Fascist, Idiot’s Delight, set in a small Italian
hotel on the Swiss border, focuses on a disparate group of international
travelers who are stranded when Italy launches a surprise air raid on Paris. To
avoid annoying Italy, the head of MGM, Louis B. Mayer, ordered the story's
setting changed to an unnamed country whose inhabitants spoke Esperanto instead
of Italian. There also was to be no
mention of Fascism. The Italian consul in Los Angeles was given final script
approval, and MGM previewed the film for representatives of the Italian
government.
When
Sherwood, who wrote the screenplay, was asked if he had had any collaborators,
he ruefully replied, "Yes—Mussolini." Expurgated and defanged, Idiot's
Delight was roundly panned by the critics when it was finally released in
early 1939. And despite all MGM's efforts to placate Italian
sensibilities, Italy ended up banning it, as did Spain, France, Switzerland,
and Estonia.
SOURCE: Olson, Lynne. Those Angry Days: Roosevelt, Lindbergh, and
America's Fight Over World War II, 1939-1941 (New York: Random House, 2013),
pp. 362-363.