Note: the following is satire.
Though I myself haven't seen the film, it is almost impossible not to think that Lacan had watched Snakes on a Plane, because his conception of alterity is so closely aligned with the film's revolutionary mise en scene. Indeed, my reading below is deeply invested in resisting the tired old "grand narrative" of "actually watching the film," which essentializes "experience," and delegitimates the kinds of liberatory theoretical praxis I have memorably justified elsewhere.
The eponymous "snakes" here are clearly the wild slithering irruption of the Real, while the "plane" is the Phallus that operates in the angular, metallic register of the Symbolic. The film thematizes the rebellion of the Real (the resisting third world subaltern, who also represents the death-drive) over the tyrannical, inscribed authority of the Aviational Master. Note that the deadliest of the snakes on this particular cinematic plane is the "Monocled Cobra," mainly found in India, which despite its Cyclopean insignia strongly suggests the film be read as a subaltern allegory of "Multitudes," arrayed in a heterogeneous composite Coalition of the Venomous against the complacent bourgeois "passengers" (nearly all of whom are fated to die), who have passively sanctioned the postmodernist military adventurism of President George W. Bush. The Snakes therefore represent the unthinkable limit in the neo-colonial discourse of the War on Terror, the exotic, "illegal" cargo that will, inevitably, bring down the brittle American frame that is the body politic in an era of the cybernetic gaze. Samuel L. Jackson is portrayed as the heroic African American man (the phallogocentric "actor," whose agency is always-already scripted), who ostensibly represents the forces of the Airplane against the Snakes, but it's clear that his true sympathies are in fact with the Snakes. Note that he insisted on leaving the word "snakes" in the title of the film, and opposed Pacific Air Flight 121, the vanilla title preferred by the studio, suggestive of nothing other than the institutionalized discourse of Air Traffic Control.
Moreover, Agamdeep Darshi, as "Ipod Girl," lies between the Phallic Plane and Counter-Phallic Snakes, and deconstructs the binary between them; her holy feminine/maternal/musical energies pacify the wild terror of the Snakes that are colonized by the white hetero-patriarchial gaze, which ethno-objectifies her in the production of the discourse of cinematic pleasure. The snakes will reveal themselves to be not a counter-Phallus, but rather an expression of the rage of the Medusa, the radical queer postcolonial feminine. What is at stake here is not a battle between "snakes" and the "plane," but rather the contest between transgressive Oedipalized subjectivity (memorably described by Jackson's line, "there's motherf---- snakes on the motherf---- plane") and the anti-Oedipal, serpentine, body-machine complex. The plane, in short, is a snake that will eat itself.