Other mistake: Lynette is talking to Susan about Zach's infatuation with Gaby. Susan asks how Zach can afford so many expensive gifts for Gaby, to which Lynette replies that he inherited his grandfather's money when he "turned 18, a month ago." However, in the previous episode, Zach reminds Gabrielle that he is two months older than John Rowland, who, it was mentioned, turned 18 in season 1, two years before.
Visible crew/equipment: When Ed opens his car door for Lynette, the camera crew are reflected in the side of his car.
Continuity mistake: When Bree throws a glass of water of Orson to wake him up, the upper part of his shirt goes from being spotted with water to being soaked.
Continuity mistake: When Tom is proposing a toast to Lynette in the bar, he's holding the coffee with his left hand. However, in the next shot he's drinking the coffee with his right hand, and when the shot changes he's holding the coffee in his left again.
Continuity mistake: During the dinner scene, Ian starts to pour his mother some wine, but in the very next shot, he starts to pour it again.
Continuity mistake: Carlos swiped every thing from the table but a fork appears behind Edie. (00:18:35)
Continuity mistake: When Lynette sends Kayla upstairs, her bag is seen both on her shoulder and in her hand between shots.
Continuity mistake: When the boy paints "witch" on Mrs. McCluskey's front door, he holds the container in his left hand and the brush in his right. But when Karen gets out and he runs away with the other kids, the two items switch positions.
Visible crew/equipment: When Carlos is speaking to Charles (Travers' father) outside about joint custody and Charles says "Y'know, I just don't get it", a boom mic and pole are reflected in one of the windows near the front door of the house.
What Would We Do Without You? - S3-E22
Revealing mistake: When Lynette tears open Tom's shirt before making love to him, you can see there are already scratches on his chest before she scratches him.
Getting Married Today - S3-E23
Continuity mistake: Gabby's hair in the beginning has her bun high on her head and her tiara is visible from the front. When Bree walks in, and when she overhears Victor and his father talking, her tiara is farther back on her head and no longer visible from the front.
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.
If There's Anything I Can't Stand - S4-E4
Continuity mistake: The amount of cream on Victor's chest during his rubdown changes between shots.
Continuity mistake: After Gabby throws John out of the hotel room, she locks the door. But when Carlos leaves the room, he opens the door without having to unlock it.
Now I Know, Don't Be Scared - S4-E6
Continuity mistake: When Carlos walks in to talk to Gabby about staying with Victor, she is drinking a glass of wine. She drains the glass except for a small sip, when she puts the glass down it's half full.
You Can't Judge a Book by Its Cover - S4-E7
Continuity mistake: When Lynette opens the trunk of her sister's car, the trunk can actually be seen opening twice.
Continuity mistake: Adam hands Katherine the note he found on the floor written by her aunt in a previous episode. Katherine is holding the paper up. When Adam walks around her in the next shot, the paper is gone and Katherine is only holding her keys/purse. The close up of Katherine (the very next shot) shows her holding the paper again.
Continuity mistake: At the end of the previous episode, an unknown someone can be seen circling Dylan's face on a picture of her and Katherine in the newspaper reporting on the Founder's Ball. In this episode, we see the cop who pulled Dylan over get back in his truck where a copy of the newspaper sits on the passenger seat. This time, both Dylan and Katherine are circled.
Other mistake: In the scene where Lynette and Tom are fighting about Lynette having taken Kayla to see a therapist, and Kayla walks away, you can hear Tom yelling about Lynette having a distorted reality and that she can't pull crap like that. In the scene where Kayla comes back into the house after conning the twins into jumping off the roof, Tom and Lynette repeat the same dialogue again.
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.
Answer: Kayla was sent away in episode 16 (The Gun Song) in season 4, after falsely accusing Lynette of child abuse. She now lives with her grandparents - probably Nora's parents.
I'm curious why we never see her again, why she never talked about, and why Tom never mentions visiting her.