Other mistake: When Carrie, Samantha and Miranda step outside of the hotel so Carrie can have a cigarette, she takes a couple of draws then throws it down on the step. She tries to stub it out with her shoe by twisting her foot on it but she (the actress) accidentally kicks the cigarette down the step, so she has to just pretend to still be stubbing it out.
Other mistake: When the plastic surgeon is giving Samantha a breast exam, you can tell that he isn't really examining her breast. He is actually moving his hand in a circular motion in the air above her breast pretending to give her an exam, but is touching her hospital gown instead. (00:20:20)