Continuity mistake: After Ben arrives, he goes outside to exterminate zombies who have been attracted to the house. There were three, the one he hit with his truck, the one on the porch, and one in the yard that looked to be wearing a leather jacket. He kills the one on the porch and the one in the yard, but he doesn't kill the one in the jacket. After he kills the one he hit with the truck and begins to walk back up the hill to Barbara, you can see him in a full, empty yard. The third zombie seemed to have disappeared.
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