Visible crew/equipment: After Spence gets weird while taking pictures of Sara at the anniversary party, when it cuts to the wide shot as Arthur says, "Okay, Garver!" a camera is visible at the right side of the screen.
Visible crew/equipment: When Spence is leaving after dropping off the pictures a stage light is reflected in the door. (00:08:50)
Visible crew/equipment: At the start when Carrie says says "it's already 20 of" look at the screen right to see the kitchen cabinets swing into place as the crew replace them. (00:00:35)
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.