Where was Dien Bien Phu filmed?
1992 French film
Dien Bien Phu (1992) was filmed in Hanoi, 1 place named in its Portuguese Wikipedia’s História, documentação e filmagem section, in Vietnam. Wikidata records no filming location for it at all, so the article is the only recorded source. Each place says where its claim comes from.
Places per Portuguese Wikipedia's História, documentação e filmagem section
Portuguese Wikipedia’s História, documentação e filmagem section names 1 place. Each links to the sentence that says so.