At the start of the film, the car is a 1996 VW Golf with a Dublin registration number. When they pull up outside the house to drop Jess off, the car has changed into a 1993 model with Kildare plates. Later, when the car crashes after they run down Craig, it has changed back into the 1996 Dublin car again.
When Craig is running from the zombies, he pulls off two planks from a fence, but the wooden bar at the top stays on and he breaks it separately. Later, when he replaces the piece of fence, the wooden bar is attached to the two planks.
Approximately half way through the film Jessica comes to Nathan's window after the disco dance held at the school to talk to him. After he chases her away he closes the window and curtain and lays back down on his bed revealing that the small dent/almost hole he put in the wall earlier via his super zombie strength to be absent from that morning.
When Jessica hides in the house, she changes clothes - is there really time for that, when you are chased by zombies?