Character mistake: In this season we see Doug smoking cigars and cigarettes. However in S2 E1 Queasy Rider, Doug is shown to absolutely detest the smell and taste of smoke from these. It is highly unlikely that he would then take up smoking.
Character mistake: The Doctor tells Carrie what's wrong with Arthur and what they are going to do. When he tells Carrie this, they are in a packed waiting room, completely violating patient confidentiality. (00:08:35)
Character mistake: When Carrie finds Tina, she mentions the "stuff" that Tina listens to at work, and Tina tells her that it's salsa. We know from previous episodes that Carrie likes salsa dancing, so shouldn't she know salsa music?
Character mistake: The woman in the store claims that the umlaut on the shoe size indicates a half size in Europe. This is wrong because the European shoe size system (used in Germany among others) is completely different from the US system. Carrie's 6 1/2 shoes would be a size 39 according to the European system.
Character mistake: In the opening scene, Doug call Carrie "Kel" which is Deacon's wife. He calls her that when he's saying they should just get a new grill.
Character mistake: Doug claims to be a Pisces, however during this episode when entering his birthday into the alarm system to disarm it he calls out 2-9-69 which shows he would be an Aquarius.
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.