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.
Plot hole: When there is a close-up shot of Charlotte and Harry's wedding announcement in the New York Times, there is a large article to the left and above. If you read what it says, it appears to actually be a tongue-in-cheek wedding announcement referencing Mr. Big and Natasha's former wedding. The college information is off (Rutgers instead of Tulane), but some of the other information alludes to their previous wedding in the Hamptons, and how they met. Also the name Natasha is mentioned several times. Yet we know that this wedding happened some time ago, so it couldn't possibly be running in that day's New York Times.
Plot hole: When Carrie calls the girls from Aleksandr's couch, she is wearing one outfit. In voice-over, she says she stayed at his apartment for 4 days. But then when she finally arrives home, she is wearing a completely different outfit. How would she have so many clothes to wear, when she didn't expect to be away from home for 4 days? She wasn't carrying any luggage or other clothing with her when she came home, either.
Plot hole: After Carrie has her strenuous night with the 'fling', she is shown lying flat on her apartment floor in the morning, as if unable to move very much. But there is a cup of coffee next to her, obviously bought from somewhere in the city. Carrie is so disabled from her injury that when she reaches the church, she is hunched over, can barely walk, and Stanford has to help her along. She is affected a great deal from her 'sex sprain' during the entire wedding. So how is it that she was able to get up and go buy a cup of coffee outside of her apartment in the morning, when she was so injured she couldn't do much but lie flat on the floor when Charlotte called her? It doesn't seem likely that Carrie would have gone to all that effort to go out and buy coffee, when she is so immobile. She wasn't able to get around well enough for a small errand.