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.
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.
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.