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.
Continuity mistake: When Carrie and Steve are sitting on his front steps discussing Aiden, Carrie is looking forward as Steve says "He lost his ability to open up and trust women." At that moment; Carrie turns her face towards Steve to her left, and keeps it there as she is appalled. But the very next shot; Carrie is suddenly facing forward again, and then starts turning her head left towards Steve for a second time. But in the next shot; she is already facing Steve, from the first time she reacted to what he said. It's clear that she had never actually moved her head after the first time.