Visible crew/equipment: When Susan sits on the couch in Edie's house, just after she throws the bra behind her and knocks the candles over, a crew member in blue jeans can be seen moving on the floor behind the couch to the right.
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.
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)
Visible crew/equipment: Just before the fire starts you can see a crew member's legs/feet on the right side of the couch. (00:38:06)
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.
Sweetheart, I Have to Confess - S3-E6
Visible crew/equipment: When Susan starts talking to Ian after trying to hide from him, a boom mic and pole are reflected in the rear window of her car for a few seconds as the camera pans over it.
Visible crew/equipment: When Karen McCluskey was stepping from the car when she was taking Bree Van de Kamp to the hospital the crew members appear in the mirror.
Visible crew/equipment: When Bree is watering the flowers in the bathroom at the hospital, a shadow of the cameraman is visible behind her.
You'll Never Get Away From Me - S2-E3
Visible crew/equipment: When Phyllis leaves in the taxi, a boom mic is reflected in the taxi's rear window.
Color and Light (a.k.a. I Must Be Dreaming) - S2-E7
Visible crew/equipment: Right at the beginning of the episode, we see a woman drop her daughter off at a strangers house. When the front door opens, a camera crew is reflected in the brass door knocker.
Your Fault - S1-E13
Visible crew/equipment: After the scene where Mr and Mrs Rowland speak with Gabrielle, a crew member is reflected on the side of Paul Young's car as he pulls into his driveway with Zach.
Visible crew/equipment: When Edie is talking to Julie and Austin about their sex life, the pole of a boom mic can be seen reflected in the window behind Edie.
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.
Visible crew/equipment: When Ed opens his car door for Lynette, the camera crew are reflected in the side of his car.
It Wasn't Meant to Happen - S2-E20
Visible crew/equipment: When Edie discovers that Karl is leaving her for someone else and drops the letter that he wrote for her, a boom mic is reflected in the windscreen of her car.
Visible crew/equipment: As Susan and Edie approach Bree to ask her about the Applewhites, a camera crew is reflected in the side of Bree's car.
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.