Nice Is Different Than Good - S6-E1
Continuity mistake: At the end of season 5, Lynette finds out she's about 6 weeks pregnant. At the end of the same episode, they do a "Two Months Later." In Season 6, Episode 1, Tom says after an argument with Lynette "Only 8 and a half more months." Lynette should be in her second trimester by then, with at most 6 months to go.
Continuity mistake: When Susan and Mike are lying on the floor in the kitchen, Susan says to Mike "You can pay the loan off by yourself" and Mike has his left hand on Susan's wrist, but in the next shot, he no longer does.
Continuity mistake: When Gabrielle asks Angie if she would like to meet Heidi Klum at the modelling agency, the magazine Gabrielle is reading is open, but when she says "Sure, she's an old friend", the magazine is closed.
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.