Revealing mistake: When Felicia pulls the urn of Beth's ashes out of the bag in the house, Harriet Sansom Harris' left hand is briefly visible, including the fingers that Felicia is supposed to be missing.
Revealing mistake: In the opening scene with Tom and Lynette, Lynette is standing in the doorway to her house but the interior in the background is different to the interior of her house. there is a blue wall in place where an open plan stair should be. (00:01:00)
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.