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 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 Ed opens his car door for Lynette, the camera crew are reflected in the side of his car.
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.
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.