Factual error: It is the weekend and Valentine's Day. We see in the following episode that it's 2006 and their calendar matches the real one, but Valentine's Day was on Tuesday that year.
Continuity mistake: When Mrs. McClusky originally comes to the door to tell Andrew about Bree being laid out on the lawn, the cover to the dial for the sprinkler system is open. In the next scene, when Andrew goes over to turn on the sprinklers, the cover is closed.
Audio problem: The opera singer seen at the beginning at the episode is dubbed. His lip movements don't quite match the tune.
Continuity mistake: When Bree grabs the twin's toy keyboard, she grabs it and holds it at a downward angle. But in the immediate shot she is suddenly holding it at an upward angle.
Continuity mistake: When Bree is at the restaurant by herself, she is wearing a ring around her neck on a chain which constantly moves position throughout the scene.
Chosen answer: Poker. They have been playing that this whole time, once a week with everyone who was invited that lived on the Lane.