“Zombies” followed a mother and child on the run, looking out for each other at the end of the world. It was important to communicate that silent bond between the two, an underlying current that makes them better suited to survival than two strangers. The mother (Amy Cooke-Hodgson) needed to convincingly toggle between the kind of earned, inside out performance one would find in near dystopian future films like World War Z and the kind of light comedy chops required to pull off the casual banter with a perfectly “normal” gas station attendant. She had to feel delusional but not crazy. It’s always tricky finding child actors but Kasey (Simon Baterip) did a beautiful job nailing the high emotional stakes. And did a pretty damn good American accent for a Northern English kid.