Frozen Pop - S2-E15
Other mistake: When Arthur decides to sleep upstairs instead of downstairs, he brings along a can of beans for a snack. It then cuts to an exterior street shot, which should be somewhere in Queens where the Heffernans live, but instead it's a shot of the corner at 14 Ave and 73 St in Brooklyn (some areas of Brooklyn and Queens may appear similar). Next shot is inside the Heffernan house in Queens. (00:11:45)
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.