Legendary director Steven Spielberg is weighing in on whether he thinks aliens really exist as his new movie, Disclosure Day, hits theaters.

The director narrates a scene from his movie that is a continuation, of sorts, of a sequence he filmed for his feature-length debut, “Duel,” in 1971.

As the race goes on, the movie veers between comedy and suspense, action and contemplation, the sounds of squealing tires mixing with sober interludes that touch on belief, reason, trauma, self-govern...