Factual error: When they are refuelling the helicopter (as a zombie approaches quietly from behind) the actor has put the gas nozzle not into the hole for the gas tank, but into one of the foot-holes that helicopter mechanics use to climb up to the top of the helicopter to do repairs. It doesn't even fit properly.
Factual error: Towards the end, the bikers are riding out of the mall, and Peter shoots one biker out of his sidecar. 1. The biker seems unaffected despite being shot through the arm with a rifle. 2. He picks up his tommy gun (notorious for powerful recoil) and starts shooting with his torn arm. Not only is this impossible, but he doesn't even wince. 3. There is nothing in front of him to shoot, and he knew there were some behind, as he got a look around when he fell off the bike.