While washing the car with Fido and Timmy, when Helen first brings out the drinks there is a shot with Fido's eye make-up clearly missing. In the next shot the make-up has been reapplied.
When Fido chases Roy Fraser into a hut, there's a bullet hole on Fido's back. That same bullet hole disappears when Fido's back is visible again.
While washing the car with Fido and Timmy, when Helen brings out the three drinks, she closes the door behind her, but the door is open in subsequent shots of the house (the stairwell inside the house is visible).
When the mother rams the barricade, she does not have the clutch engaged when she floored the accelerator. In real life the car would have stalled.
When Timmy's mother shoots the bully zombie behind the bushes, she fires her gun 9 times, which is not possible since a revolver like that only can fire 5 or 6 bullets before needing to be reloaded. However, the amount of shots fired seems to be intentionally overdone as a joke.
When Zombie Paperboy throws the paper at Mr. Theopolis's porch he clearly misses, but then Theopolis's zombie, Tammy, picks it up from the porch.
When Timmy is hiding behind the red car watching his father pull in, the hood pops on Timmy's father's car.