Visible crew/equipment: Right before Bree drives herself to the emergency room and is talking to Mrs. McCluskey, a crew member's face is reflected in the car's left wing mirror.
Continuity mistake: When Lynette is feeding her baby, we see from behind there is a backpack on her chair then when the shot changes it is not there. (00:29:55)
Continuity mistake: When Lynette comes out of the pool, after getting her boys, she is wearing high heels, but when the shot changes to a distance, she isn't wearing anything on her feet. (00:13:15)
It Wasn't Meant to Happen - S2-E20
Continuity mistake: While Susan and Edie are at the Hooters style restaurant, the amount of beer, and amount of head, in Edie's glass changes from shot to shot.
There's Something About a War - S2-E13
Continuity mistake: When Lynette and Tom are talking, Tom says "Really I got the job?" and puts down the newspaper he was just reading. In the next shot we see Lynette and you can see Tom is still holding the paper and puts it down again.
Love Is in the Air (a.k.a. What I Did for Love) - S1-E14
Factual error: Lynette's neighbor tells her that the pot Lynette's sons gave her is really hers, the neighbor's, and she bought it in Costa Rica. She turns the pot over to show Lynette that the price is marked on the bottom, with a number followed by the letter p. One supposes that the p might stand for peso, except that the currency of Costa Rica is the colon, which consists of 100 centavos. No p in sight.
Continuity mistake: When Bree goes to see Zak, in one shot her hands are intercrossed, then in the next her arms are crossed. (00:17:55)
Continuity mistake: On the note Mary Alice receives that leads to her suicide, the position of the three sentences changes throughout the series. In episode 1.1 (Pilot), all three lines are written on the top half of the note (above the crease), but in later episodes the first two lines are on the top and the third is on the lower half. The left margin also gets smaller, and the handwriting varies slightly.
There's Something About a War - S2-E13
Continuity mistake: As the nurse is talking to Susan about the operation, the folding of the paper the nurse is holding on the clipboard changes between shots. First it is half folded over, the next shot it has been folded right over and is being held right down. After this shot it changes again and is now folded back without her moving the paper.
Continuity mistake: When Lynette and Gabrielle are talking to Paul, the boxes Gabrielle are holding change position between shots under her arms. (00:34:30)
Continuity mistake: When we see Lynette driving her kids, in the first shot we see some red, blue and white decoration in the front of the car to the right, then when the shot changes it's in the centre. (00:13:50)
Running to Stand Still - S1-E6
Visible crew/equipment: When Susan is following Paul in the car she borrowed, we can see the reflection of a crew member on the right hand side of the window. (00:18:15)
Continuity mistake: When Julie is leaving we see that she leaves the door open and then it closes with a slight open gap, yet just for one shot the door is completely closed, then it's open again. (00:09:50)
Running to Stand Still - S1-E6
Continuity mistake: When Lynette is talking to Jordana the items on the table keep changing position in between shots. (00:29:30)
Running to Stand Still - S1-E6
Continuity mistake: In one shot during the poker scene the baby moniter changes position to the other side of Lynette then back again. (00:13:30)
Mother Said - S4-E15
Continuity mistake: When Orson is on the phone with his lawyer, he sets down the notepad with a page half filled with writing at the front. However, later in the scene Edie walks into the room and the front page of the notepad is full of writing, plus there's an extra line in the first paragraph. No one was around to move the page as Orson was in the shower.
Now You Know - S4-E1
Continuity mistake: When Bree grabs the old lady's wrist to keep her from touching her belly, her thumb is on the palm side of the lady's wrist. Then when the shot changes, Bree's thumb is now on the back side of the lady's wrist.
Continuity mistake: Lynette is giving a speech during Renee's wedding. In some shots, she holds the microphone in her right hand and a glass of wine in her left hand. In other shots, she holds the microphone in her left hand and a glass of wine in her right hand. (00:32:40)
Continuity mistake: At one point in episode 1.2 ("Ah, But Underneath"), Susan looks at the note used to blackmail Mary Alice and we can see that it has been folded twice and become somewhat crumpled. Two episodes later in "Who's That Woman?" (1.4) when the girls show the note to Paul, it is almost perfectly smooth with a single horizontal crease.
Chosen answer: Poker. They have been playing that this whole time, once a week with everyone who was invited that lived on the Lane.