Continuity mistake: When Rex Van De Kamp is at the restaurant, his fork is half way over his napkin then in a later shot it's completely on the napkin. (00:26:50)
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)
Continuity mistake: When Andrew is talking to his mum, Bree, on his bed, we see him put the magazine down, yet in a later shot it is no longer there. (00:38:10)
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)
Continuity mistake: In the restaurant, Bree makes a salad for Rex at the salad bar. It is fairly tall with lots of tomatoes. The salad she gives him is flatter and missing many of the tomatoes.
Plot hole: Several days must have passed between the teaser of this episode and the rest of it, since Gabrielle has had time to make up (very professional-looking) cards and posters, gotten several dozen volunteers and reserved dresses for many of them, yet Paul has only just gotten around to disposing of Mrs. Huber's body and trying to wash the blood out of his shirt. Even if we assume the teaser takes place right after the end of the last episode (when Paul murdered her), that's still several days of keeping a rotting corpse and enough evidence to put him away for life around his house.
Visible crew/equipment: In one of the episodes, Gabby has her Maserati car taken from her by the repo guy. When he pulls off, the car is towed behind him. Clearly reflected in the metallic paint of the Maserati is the crew, with boom, camera and everything else.
Continuity mistake: When Lynette gives her husband his photo, the position of the photo changes in between shots. (00:13:05)
Every Day a Little Death - S1-E12
Continuity mistake: Bree arrives home carrying a package in her left hand and bags in her right. In the next shot, when her phone rings, the package is gone, the bags are in her left hand and she answers the phone with her right. (00:07:10)
Continuity mistake: When Karl is speaking to Susan whilst she's in the towel, we see in one shot his chin is resting on his palm, then when the shot changes he tilts his head and then moves his fingers to his chin then when the shot changes his chin is resting on his palm again. (00:25:00)
Your Fault - S1-E13
Audio problem: At the school dance, the students are all dancing at a rapid pace when the music playing is a slow song, indicative that the music was dubbed in later.
Impossible - S1-E15
Continuity mistake: Episode 15- When the housewives are sitting on the porch discussing Mike Delfino, Teri Hatcher's green shirt keeps changing positions in the shot. It goes from down around shoulders to close to her neck and back.
Factual error: This is for one episode 1-23. In the beginning, there is a shot of a calendar for March 1990. It shows March 1st being a Wednesday. March 1, 1990 was a Thursday.
Love Is in the Air (a.k.a. What I Did for Love) - S1-E14
Continuity mistake: When Susan's reading her Valentine's card, in the shot over her shoulder she closes it. The angle then changes so we can see one of the other housewives approaching - her card's now open and she shuts it again.
Love Is in the Air (a.k.a. What I Did for Love) - S1-E14
Continuity mistake: Bree Van De Kamp is sitting in a chair talking to her husband Rex while knitting. In one shot, after the camera goes back to her, the object that she is knitting disappears, then re-appears when the camera comes back to her later in the scene.
Continuity mistake: When Mike is taking his dog to the vet, we see that Susan's hair is covering her ear in all the shots except the last one when her hair is behind her ear to show that the earring is gone. (00:39:30)
Continuity mistake: When Bree is about to leave the hospital she picks her bag up with her left hand to put it on her right shoulder but when the camera angle changes she's put the bag on her left shoulder with her right arm.
Deliberate mistake: When Susan falls through the floorboards of Mike's house she uses the nearby towel to try and get the dog Bongo to help her. If you watch at the different angles the position of the dog keeps changing. When it shows Susan from behind the dog is almost right next to her face and stepping on the towel. In the shots from in front of Susan the dog is nowhere near the towel or even in the shot. This mistake looks more deliberate as the front on shots of Susan, the dog would likely have blocked her face from the camera.
Love Is in the Air (a.k.a. What I Did for Love) - S1-E14
Continuity mistake: When Lynette is chasing her neighbor out of her boys' bedroom and has a pillow in each hand, one is spotted and one is light blue. She raises the light blue pillow to throw at the neighbor. When the camera switches to the bedroom door, its the spotted pillow that hits the door behind the fleeing neighbor.
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.