There are profanities aplenty in “Wild Horse Nine,” as there are in all McDonagh’s movies and plays. (Cut out the F-bombs and most of them would run barely an hour.) And the vast expanse of Easter Island, majestically filmed by the cinematographer Ben Davis, is astonishing to behold. (Lee himself can’t resist filming with a Super 8 camera, and his grainy images add welcome blips of texture.) Feral horses roam the landscape, and they give the movie both its title and its desired genre: McDonagh strives for the laconic sweep of a classic Western. But not all material can command a space this vast, and I suspect that John Ford himself might have struggled to wring much poetry from Chris and Lee, two ugly-American blowhards wisecracking their way around paradise. Really, the shenanigans could have been transplanted anywhere: picture two guys farting at Stonehenge for an hour or two, only to realize, like the ancients before them, that it makes an awfully nice burial ground.

Within such comedic confines, and with a surprising dearth of violent mayhem, “Wild Horse Nine” strains for thematic expansiveness. Ostensibly, the film is about the mixed blessings of friendship, the soul-corroding nature of violence, the horrors of U.S. foreign policy, the possibility of redemption, and the inescapability of death. But it’s the stiffest, least cohesive film on those subjects you could imagine. McDonagh organizes his scenes into thematic blocks, and whenever he loses interest in one block he simply switches, mechanically, to the next. The conversations that he’s written for Chris and Lee toggle between humor and pathos, between self-satisfied snark and self-conscious elegy, and there’s barely a moment when you don’t hear the grinding of tonal gears. (You hear it in the music, too; the Rolling Stones’ “Out of Time” isn’t the subtlest of needle drops.)

McDonagh’s dialogue is famed for its staccato crackle, but here he slows the characters’ rhythms, as if to accommodate the diminution of Chris’s body and mind, and packs dead air around everyone’s lines. Yet within those rhythms Malkovich does locate odd, narcotized flashes of poetry. His voice is lower and shakier than usual, and the gleam in his eyes sometimes goes ambiguously dull: are Chris’s mental lapses real, or part of some long con? Chris hasn’t lost his saucy erudition; one of his funnier bits is a mid-breakfast monologue on why “gay countries,” like France, produce the highest-quality cheeses. But he seems on precarious ground, no longer certain of his punch lines. He is also rediscovering the guilt and terror of his Catholic upbringing, and he wonders if, after a life spent overthrowing democracies—the coup that will depose President Salvador Allende is in the offing—he has a chance in hell of entering Heaven.

Easter Island is, of course, dotted with towering volcanic-stone figures with large, elongated faces. Chris and Lee refer to them as “the big heads,” and when a tourist couple gently note that the Indigenous term is “moai,” Lee erupts in fury—though Rockwell, who’s good at modulating an explosion, makes clear that Lee is exaggerating his rage for Chris’s benefit. Earlier, at the Santiago airport, they had an awkward run-in with two Chilean college students, Monica (Mariana di Girolamo) and Alicia (Ailín Salas), one of whom explained that the Indigenous name for Easter Island is Rapa Nui. “You shouldn’t even know the word ‘Indigenous’ at your age,” Chris replied.

It’s telling that McDonagh hammers the word “Indigenous” repeatedly and contemptuously—as opposed to, say, “local” or “Polynesian.” Back in the seventies, the term was less prevalent in English than it is today, but McDonagh, not for the first time, is eager to mock the language of the contemporary liberal scold. Farrell’s “In Bruges” character wasted no opportunity to call a dwarf a midget; in “Three Billboards Outside Ebbing, Missouri” (2017), McDonagh’s most pugnacious and polarizing work, Rockwell played a racist cop, annoyed that “persons of color” had replaced his favorite epithet. You could argue, I suppose, that a film shouldn’t be reduced to its characters’ politics. But, by now, it’s hard to assume that these smug linguistic sensitivities—wielded only, of course, in response to other people’s smug linguistic sensitivities—belong to anyone other than McDonagh himself. And they speak to the narrow view that he takes of his chosen setting and the harrowing historical episode into which he’s seen fit to shoehorn his characters.