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.
Plot hole: When Carrie runs into Aiden on the street, he tells her that he 'married another furniture designer'. Although Carrie is happy for him, it doesn't seem likely that she wouldn't have known about this. Steve and Aiden are business partners and close friends, and Miranda is very close to Steve with their baby. Carrie would have undoubtedly heard about Aiden's marriage through the 'friends grapevine' before that, as news that big wouldn't just slip under the radar. Someone would have told her, so it isn't logical that she is just now finding out about Aiden's marriage.