Continuity mistake: When Carrie is lying on her bed, she is wearing yellow pants over a green top. The top portion of her pants is unbuttoned/unzipped as she moves. But after she picks up the phone to call Big, she is sitting up on her bed, and her pants are suddenly buttoned/zipped completely up. There was no opportunity in this sequence for her to have closed her pants.
Continuity mistake: When Carrie and Mr. Big are arguing out on the street in front of her apartment, there is a shot of her holding the leash for Pete the dog in both hands. But suddenly as she is yelling at Mr. Big, you can see her throw both her hands up in the air and touch her head. She is not holding the leash at all. Then seconds later; there is a shot of her legs as Pete is running off, dragging the leash from her body and waist as if she is still holding it.