Late in Steven Spielberg’s new film, Disclosure Day, a former nun-to-be calls the abbess of the convent she left behind. The world is about to learn that aliens have been living on Earth for decades.

In the run-up to the release of Steven Spielberg’s “Disclosure Day,” I felt a whiff of desperation in the air. The director, who is seventy-nine, had had two commercial flops in a row, “West Side ...