Other mistake: The first time Rachel brings the team coffee, she has six coffees on a tray. There's five cappuccinos and one regular coffee for Harry. On the tray there is five coffees on one side and one coffee at the other side, obviously being Harry's regular coffee, so that Rachel would be able to tell the them apart. But when she gives Harry a coffee, she gives him one of the five standing together, so he obviously got one of the cappuccinos.
Other mistake: When Harry gets out of the truck at the motel to retrieve E.L.F., there appears to be a blue & white storefront sign in the background that is lit, when the rest of the town is dark due to no power. Either that, or it is a really bright, white, non-electric sign that has been completely unaffected by the ash that is coating everything else in town.