Continuity mistake: When Bree is preparing a care package to ship to Andrew's camp, she sneaks some lemon bars into the package, and quickly closes the two side flaps of the cardboard box, leaving the end flaps out. In the next shot, she is immediately taping the box with all flaps down.
Continuity mistake: Parker is tearing the flowers apart until there are none. In the next shot, there are some flowers left, and when he jumps off the chair, the flowers have gone again.
Audio problem: When Lynette tells her sons to clean their teeth in the bathroom, the boys turn around and in the mirror you can see Lynette saying the same thing with no sound.
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.