Every person should have their escape route planned. I think everyone has an apocalypse fantasy, what would I do in the event of the end of the world, and we just basically - me and Nick - said what would we do, where would we head?
Both me and Edgar are firm believers in never underestimating or talking down to an audience, and giving an audience something to do, to give them something which is entirely up to them to enter into the film and find these hidden things and whatever.
Also, if you watch the film once, there are lots of things that you won't get because there are punch lines in the first act, the setup to which isn't until the second act.
That's what we wanted to get across in that moment, particularly when Shaun goes to the shop when he's all hung over. He doesn't notice any of the zombies around him just because he never had before, so why should he at that point?