Corrected entry: When they get to Debra's home, they open the door and have to disarm the alarm. She punches in the wrong number, and the alarm goes off. However, they find the family (now zombies) inside the house. The alarm should have gone off by the family's movements before the group got there.
Corrected entry: In the scene where Riley is in the kitchen with Deb and Tony, Riley says in reference to Cook "I wonder if she ate the rabbit". Later in the pool a male figure in a chef's outfit, presumably Cook, can be seen. This is even clearer in the DVD special effects featurette.