Audio problem: After Carrie returns from dinner, she is using the computer when suddenly Aiden ("AidenNYC") is shown logging onto her AOL Buddy List (upper right of her computer screen). But for some reason, the show uses an 'IM Chime' sound. When someone logs onto their computer and appears on your Buddy List, it makes a different noise (usually a door-opening sound). The 'IM Chime' sound only happens when someone actually sends you an Instant Message. In this case, Aiden had not IMed Carrie. There was no IM on her screen, and he only appeared on her Buddy List. (00:18:40)
Suggested correction: The sounds for logging on or IM'ing can be changed under the settings.
Because Carrie was brand new to the Internet, she had very little knowledge of how it works. She would not be advanced enough to know about IM settings, or how to change them. (This is clear when she humorously tries to 'hide' from Aiden's IM on screen, thinking he could see her physically). And it isn't likely that she would have changed the settings if she was just starting to use the Internet and had little experience with it. They used the wrong sound on camera.
I heart ny - S4-E18
Continuity mistake: When the horse drawn buggy is pulling over to the curb in front of the hospital, you can see it dodging traffic and cars. But after Carrie leaves and the buggy pulls away with only Mr. Big, suddenly there are no cars or traffic in sight. The entire street from that direction appears to be completely empty. (00:22:50)
The real me - S4-E2
Character mistake: Miranda, Charlotte and Carrie are sitting in the cafe waiting for Samantha, when she runs in late, armed with her photos. Just before she'd arrived, a waitress had come to take their order - Carrie ordered a drink but nobody ordered food, but when Samantha offers the photos to look at Miranda says something like "But only till the food arrives." They didn't order any food.
Continuity mistake: Right before the '3-way'; Samantha takes off the top of her lingerie/dress and pushes it down to her waist, to reveal a strapless black bra she is wearing underneath. She does this in response to the younger girl removing her top, and they are both obviously getting ready for the main event. But in the next shot when Samantha is kissing Richard in bed, she is suddenly wearing the black lingerie/dress pulled back up over her shoulders again. Why would she put the dress back on, after removing it for sex? (00:23:10)
Continuity mistake: When Mr. Big comes up to the cabin to talk to Carrie, he isn't wearing glasses. After he drinks too much wine, they decide he has to stay the night at the cabin. Aiden throws him a pillow and blanket. Right when the blanket hits Mr. Big as he is sitting in the chair, you can suddenly see what look like some sort of metal frame glasses hanging vertically/falling off from Mr. Big's face, as if they were knocked off by the blanket. Where did the glasses come from? He wasn't wearing them just before that. (00:24:40)
Ghost town - S4-E5
Revealing mistake: When Samantha and Maria are in the bath tub arguing; Samantha decides to leave, and suddenly gets up out of the water. She is not wearing anything from the waist up; but if you look closely just at the end of the scene, you can briefly see that Kim Cattrall is actually wearing some sort of minimal dark undergarment below her waist to cover herself. You can see a black strip of material across her hips. (00:11:20)