Other mistake: Bree is drinking wine with Karl, but before in other episodes and season and episodes and seasons after, she sternly says she does not drink because she was an alcoholic.
Other mistake: When Bree goes to talk to Eddie Orlofsky's mother, she introduces herself as "Bree Hodge." However, she proceeds to talk about how Eddie likes her daughter Danielle, but her daughter "doesn't return his feelings, she spends most of her time with the other cheerleaders." In the scene before, Eddie had also mentioned that he liked a girl "from school." The problem is at the time that Danielle was in high school, Bree was not "Bree Hodge", but "Bree Van de Kamp." She hadn't even met Orson Hodge then. (00:19:10)
Other mistake: Throughout the sixth season Eddie Orlofsky attends school with Porter Scavo, and Danny Bolen, witch means they must be close in age. However, in season 6 episode 20, it is revealed that Eddie was in high school the same time as Danielle. This does not make sense due to the fact that while Danielle was in high school, Porter and Preston were about 10.
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.