Continuity mistake: In the episode "Secret Sex," Samantha and Carrie are hanging Carrie's poster in her apartment. In one shot, the whole poster is pinned to the wall and in the next shot, the bottom left part of the poster is curling up. After another shot of Samantha, the poster is pinned perfectly to the wall again.
Continuity mistake: Carrie and her friends are in the City, waiting for the bus with her photo on it to drive by. When it does, there is a shocking hand-drawn image of a sexual nature near her head on the poster. In the next shot of this image, which is more of a close-up; it's a different drawing. Very similar, but obviously not the same drawing as shown the first time.