The initial warning is given before “Vice” even starts, in an onscreen note: It’s a “true story,” we’re told. But it’s hard to be strictly factually accurate, the note adds, because Dick Cheney is such a secretive bastard. So it’s really the former vice president’s fault if anything in the movie happens to be wrong.

Yet at the end a character will break the fourth wall to assert that the whole thing is factual and to add, sarcastically: “Because I have the ability to understand facts, that makes me a liberal?” That sounds like an invitation to consider the facts and logic of “Vice.” I accept.

Near the start, writer-director Adam McKay implies that Cheney’s father-in-law murdered his mother-in-law by drowning her in a lake. Huh? What does this have to do with Cheney? Is there more evidence for this than is presented in the movie, which is none?

After dropping some light murder innuendo, McKay just bustles on. Cheney (Christian Bale) is portrayed as a dirtbag who was kicked out of Yale for boozing and brawling. When he first arrives in Washington, he asks others what he is supposed to believe, because all he knows is that he wants to work for a charismatic White House official, Donald Rumsfeld (played as a sort of Machiavellian yokel by Steve Carell).

That’s the kind of lazy screenwriting that typifies the film. It’s easiest for McKay to just put left-wing fantasy dialogue in the mouths of his characters.

He does this even more notoriously with the young Antonin Scalia, when the then-future Supreme Court justice says, “If you, like myself, happen to believe in Article II of the Constitution…” Scalia continues by telling young Cheney that Article II — which grants the president a lot of authority, especially in wartime — gives the chief executive the power of “absolute executive authority, and I mean absolute.”

Article II doesn’t say the president can do absolutely anything, and Scalia wouldn’t have said so. It’s the equivalent of showing a young President Barack Obama joining the Communist Party of Kenya while praying to Allah.

But when it comes to conservatives, anything goes.

The film blames Cheney for the launch of ISIS, on the absurd ground that the vice president publicly mentioned the name of terrorist Abu Musab al-Zarqawi, thus making him a superstar. At the same time, McKay claims Cheney didn’t pay enough attention to Zarqawi and let him do anything he wanted for a year, then cuts to the 2005 London transit bombings.

Yeah, remember when the Bush administration was doing nothing about terrorism?

“Vice” claims that President George W. Bush started the Iraq War not because he and Cheney thought it was the right thing to do, but because they needed a PR stunt to make Americans like their team.

This logic is bizarre: The son of the president who enjoyed 90 percent approval ratings after winning his own war with Iraq, then got 38 percent of the vote when he ran for re-election the next year, considered war with Iraq the best way to win re-election?

McKay marvels at the sinister persuasion efforts of the Bush ­administration, which marks a bit of a change from that era, when Bush and his team were treated as colossal dummies by the Hollywood liberal set.

If the Iraq War was obviously an evil Republican plot to hoover up all of the oil and benefit Cheney’s Halliburton cronies, it’s strange that lefties like Hillary Clinton backed it.

I had thought we had heard the end of liberals’ obsession with waterboarding suspected terrorists and with imprisoning them at Guantanamo Bay, given that Obama once assassinated an ­unarmed American teenager with a drone strike, killed other Americans with drones and kept Guantanamo Bay open.

But no. McKay uses “Vice” to rage against “enhanced interrogation” techniques. If Cheney had simply assassinated instead of waterboarded those three suspected terrorists, and killed some innocent bystanders in the process, McKay would either have to be OK with that — or simply clarify that things that are fine when Democrats do them are outrageous when Republicans do them.

Debunking all of these feeble points again, 15 years later, is as tiresome for me as it is for you, but memories fade while movies like “Vice” linger on the internet forever, shaping conventional wisdom and, worse, becoming conventional wisdom.

This essay was adapted from National Review, where Kyle Smith is critic-at-large.