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.
Plot hole: In this episode Carrie runs into Aidan, who now has what looks to be about a 6 month old baby (Tate). This doesn't seem possible, as Carrie and Aidan would have only broken up about a year ago, and Miranda was around 6 months pregnant when they broke up. Brady is only about 5 months old at this point in the series, leaving Aidan only roughly 8 months to have this baby - but Aidan lay in bed for about a month and then dated Nina Katz for awhile. Timeline just doesn't seem to fit.