Revealing mistake: The scene where Charlotte is shown sleeping with her new 'plus one' to the next morning was all filmed in entirely one sequence, real time, without any editing. Therefore, Charlotte had to change really quickly into her lingerie, and get into position for the morning shot in a very short period of time. As the camera pans away from Charlotte taking off her clothes at night, there is a mirror on the wall behind her. If you look closely at the mirror, Charlotte appears to fall over quickly, and then suddenly roll/move to the right side and get off of the bed, as if to change into her morning outfit.
Revealing mistake: When Samantha is walking down a busy NYC street talking on her cell to Carrie, you can see a man in a blue jacket walking right behind her. The next shot of him; he suddenly pulls out an obvious black camera and takes a photo, aiming it directly at Samantha in front of him. This is apparently not an 'extra', but someone on the street who wanted to take a picture of Kim. There are also a lot of other people in the background walking behind her at this point. But in the next shot of Samantha still walking on the same street and talking on the phone, there are suddenly no people right behind her at all. It's an empty space, and no time has passed for them to have dispersed. They may have cleared the area behind her; because people weren't behaving properly during filming, such as the man taking her picture. This would normally be a continuity error; except that in this case I believe the sudden change in background was due to the guy taking the picture inappropriately, not just a slip in background filming.
Revealing mistake: During the scene when the girls are walking down the street, 'strutting' fully dressed up on their way to the Navy party, look behind them in the distance. There appears to be a great crowd of people gathered behind what might be a barrier. These look like people just watching the filming. This is more clear at the very beginning of the scene, when the girls first begin walking down the street. Also, in the TBS web site in the episode guide, there is a photo of this very same scene shot from a different side angle. You can see a definite barrier on the sidewalk to the left, filled with onlookers who are watching the filming. Thus, it's possible that the people in the rear visible in the show, are the same.
Revealing mistake: When Carrie and Berger are talking on the grass, Berger suddenly gets up to leave. He grabs his jacket which Carrie is sitting on, knocking her over. As she falls back, you can see her quickly pull the front of her shirt over herself to make sure it covers her pregnant belly. Also, as Carrie starts to get up, there is a point where her shirt falls forward, and you can see Sarah Jessica Parker's pregnant bulge from the side.
Revealing mistake: When Carrie is watching TV in her apartment, she uses the remote to click off the TV after SNL is over. There is a close-up of the TV screen, reflecting the room in front of it. You can see a round table with a lot of stuff on it, the windows/curtains and desk, and what appears to be a square ottoman of some kind. But Carrie is nowhere in sight, there is just a blank wall reflected where her image should have been. She is directly facing her TV, as shown from the angle of her perspective as she clicks it off. We should be able to see her somewhere within the television reflection, but she isn't there.
Revealing mistake: During this scene, Samantha throws a cantaloupe through the window. As Sarah Jessica Parker reacts to the incident, you can see her very pregnant belly from the side, especially as she bends over. According to the commentary, she was about 7 months pregnant at the time.