In "Bay of Married Pigs", when Carrie and Stanford run into her old boyfriend, a bus is visible behind him. In the next shot, the bus is not there, However, in the shot after that, the bus is visible again.
When Carrie, Samantha and Charlotte arrive at the party, their clothing changes when they enter the apartment: Samantha's halter dress changes from green to blue and the straps on Carrie's dress are noticeably thicker.