Continuity mistake: On the part where Joyce is arguing with Professor Miller (where she cuts her finger) watch her shoulder. As the cameras goes from her to Professor Miller, her purse strap keeps coming and going.
Continuity mistake: When Steve hits redial on the cell phone it goes to Professor Miller's office, but the last number he called was his cell phone.
Chosen answer: It was actually the bloated corpse of Kevin that let Emery's mother in, so he wasn't alive when letting her in.
Bishop73