Revealing mistake: When the Thug Zombie has been torn in half and it is crawling toward Lionel, you can see the shadow of the actor's body being dragged behind it. (01:16:05)
Revealing mistake: When Lionel has just finished massacring the zombies, Thug Zombie appears at the top of the stairs. If you look closely you can see his real pair of legs near the window Lionel flew out of earlier. (01:28:35)
Revealing mistake: When Paquita discovers the zombies tied up in the basement and convinces Lionel to kill them, he gets the "poison" and injects them with it. Look closely: the shelf that he gets it off is the same as the VETS' shelf in a much earlier scene (Even the bottle of tranquilizer that Lionel dropped is back there).