Whole thing happens inside a brownstone building. On the ground floor, there's a bar, large lcd screens mostly doing newsy channels, patrons comment, drinks etc. On the third floor there's an apartment, inhabited by an old guy, kinda depressed recluse type. He has a tank with five fishes.
In bar, news report, Somali guy not speaking any English and not dressed for the season found very disoriented in the lobby of Chicago theater.
In apartment, all of a sudden, tank has only four fishes. Fifth fish flapping desperately on floor. Old guy is weirded out, picks fish up, sticks it back in tank.
In bar, bunches of various weird news reports, random people missing, cars missing, airplane missing, random people found, random accidents with cars suddenly driving off cliffs and whatnot. One guy in swimsuit rubbing tan lotion on disrupts Winter Games in the Alps. He claims he was at the beach. Generally the idea is that suddenly people find themselves in random places, played for maximal weird lulz.
In apartment meanwhile (interspersed with above), old guy getting increasingly depressed. He's shown contemplating a bunch of psych advertisings. He's also shown randomly teleporting around his apartment. He eventually hangs himself.
In bar, newscast shows "fringe scientist" who presents his theory to explain all the recent weirdness : according to him, "reality" really is a matrix type construct, probably abandoned by its original creators and now starting to decay, which is why people get relocated. He's calculated that in general any moving object has about a 50% chance of randomly appearing in another location somewhere on "Earth" (just the ground tho, not ocean or midair) for every 100'000 kilometers it moves times the number of people it contains. This has to do with the way objects are iterated by the software running "the universe".
The film closes on the savant's observation that the glitching is slowly increasing, and if his calculations are correct, person swapping should start sometime in the next year.