Anachronisms: The type of fireworks display in the 4th of July scene was unheard of in the United States during the 1960s. At that time, almost all fireworks used in the U.S. were made in the U.S., and were generally fired one at a time. Chinese-made fireworks did not become prevalent in the United States until after trade relations were opened up with China in 1972. The low-level Chinese-style fireworks shown in the film were not imported into the United States during the 1960s and did not become popular in fireworks displays in the U.S. until the 1990s at the earliest.
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