Continuity mistake: During the scene in which Lionel is in the basement attempting to sedate the nurse and his mother, he is startled by a falling crockery. After the rat runs past him, the nurse attacks him. He stabs her in the nose with the syringe, however, the following shots show the syringe is embedded in her eye.
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).
Visible crew/equipment: After the uncle has been torn apart by the mother, he goes after Pequita and you can see the wire holding his head up. (01:27:50)
Visible crew/equipment: When 3 of the zombies are high on Animal Stimulants and are going rabid at the house party, several girls have locked themselves in a room. A guy starts to crawl in with no flesh from his waist down. In one of the shots as they pull him in, you can see his REAL body as the skinless legs are kicking (Look for a pair of black pants). (01:12:35)
Plot hole: After Lionel locks zombie mum and the nurse in the basement, he tells his girlfriend that the went to the hospital in the nurse's car and she leaves, but wouldn't she notice that the car is still there?
Continuity mistake: When the top of the zombie's head slides toward Rita, the floor around it is clean. As soon as the shot changes, there's blood all around it, and then it changes again, when Paquita kicks it. (01:25:20)