Visible crew/equipment: When Carrie is sitting on their bed talking to Doug about falling in love with her pretend (model home) family, you can see the shadow of a boom mic move on the closet behind her. (00:13:25)
Visible crew/equipment: When Doug and Carrie are talking about the sketch of Carrie on the fridge and Doug says, "Man, he's got some skills" (talking about Major), a boom mic is visible at the top of the screen.
Answer: Sara hasn't been mentioned in later episodes, and it suggested in later episodes that she never existed, and that Carrie is an only child. Kevin James stated that the producers couldn't think of an good plots to use with Sara, so they left her out.