Other mistake: Carrie says that Deacon doesn't drink or smoke. Many episodes have shown Deacon drinking a beer or a margarita.
Other mistake: During the picnic softball scene, there are mountains in the distance. There are no mountains in or near Queens New York. (00:05:40)
Thanks Man - S6-E9
Other mistake: When Deacon's youngest son says "is that man going to freeze, daddy" you can see the older son mouthing the lines. (00:06:16)
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.