There are moments in Good Night, and Good Luck, the new play by George Clooney and Grant Heslov opening on Broadway tonight at the Winter Garden Theatre and starring Clooney as pioneering TV journalist Edward R. Murrow, when the anti-authoritarian passions of all three men are made very clear. Anti-McCarthyism in Murrow’s case, anti-Trumpism for Clooney and, one presumes, Heslow. Unfortunately, more often than not, that clarity comes through speechifying, minor-key tirades and copious use of ’50s-era TV clips that make plain the all-too-obvious parallels between then and now.

We know when, in history and in the play, the inevitable “Have you no sense of decency?” will arrive to put Senator Joseph McCarthy out of America’s misery. When, the play not so subtly wonders, will Donald Trump face the same path?

Making clear-as-day the similarities between those long ago days of McCarthyite propaganda and today’s Trumpian “alternative facts,...