Its existence seems like a weird hallucination: A movie titled “9/11,” starring professed truther Charlie Sheen, arriving in theaters just three days before the somber 16th anniversary.

Even after seeing the trailer and taking in the wildly tone deaf poster — with Sheen, Whoopi Goldberg and Gina Gershon superimposed over the Twin Towers — it’s possible to maintain that illusion.

This must be some kind of joke, right?

Alas, there really is a Charlie Sheen 9/11 movie that absolutely no one needed and it really is a spectacularly misconceived piece of garbage, in which the optics of a substandard disaster movie are discomfortingly applied to this unfathomable tragedy.

Director Martin Guigui, who also co-wrote this adaptation of the stage play “Elevator,” intends for the film to stand as a testament to the resilience of those who survived the attack.

It’s about five people trapped in a north tower elevator (Sheen and Gershon are among them) and the operator (Goldberg) desperately seeking a way out.

All the tropes of a run-of-the-mill genre picture are here: the hurried introductions of the ensemble; the single-trait archetypes passing as characters; shot after shot of minor figures staring at TV coverage.

It’s deeply morally suspect to turn the attack on the World Trade Center into the background for this sort of low-grade entertainment.

Yet, even if one meets “9/11” on its level and regards it as a minor character study or forgets all about the magnitude of the event at hand, the movie still fails.

The individuals stuck in the elevator are spectacularly boring. Sheen does a slightly subdued version of his husky-voiced manic shtick and the others (especially a character detailed in the official description of the movie as “breaking up with her sugar daddy”) have such little personality they might as well be inanimate logs. The actors try to gin up a requisite level of panic and despair, but it all seems desperately forced.

If the people stuck in mortal danger don’t seem to feel much, it’s a lot to ask of the audience. The amateurish aura extends to the cinematography, which fails to transform the elevator into space dynamic enough to establish the needed sense of claustrophobia. The diversions to other scenes of the unfolding crisis, such as the rescue efforts of firefighters, seem to have been deliberately scaled back for budgetary reasons. With the level of filmmaking craft applied, it’d be midnight movie fare if it weren’t for the seriousness of the subject.

It’s possible to make a worthwhile movie about the rescue efforts — Oliver Stone managed it with “World Trade Center” by zeroing in on the heroism of Port Authority officers trapped in the rubble. There’s a reason to tell that story and power in its tribute to the first responders who sacrificed so much on that day and continue to do so now.

Or, if you’re a filmmaker interested in doing this in the future, you could just watch “9/11” and do the opposite of everything.