The scene where the lady blinded the dog with the paint. It was inferred that the survivors were familiar with the dogs and had encountered them before. If so, why not just always carry paint or something else to blind them with? Admittedly, a nitpick. The episode was awesome, especially the cinematography.
*Black Mirror* is an anthology series created by Charlie Brooker featuring speculative fiction with dark and sometimes satirical themes which examine modern society, particularly with regard to the unanticipated consequences of new technologies. Seasons 1 and 2 aired on Channel 4. Seasons 3 and 4 aired on Netflix.