The Undergraduates

Stephanie Savage noted that the show had been working closely with prominent members of New York's fashion industry, citing Vogue magazine, the CFDA led by Diane von Fürstenberg, and the New York City Company to integrate the episode into the event. Real footage on the September 10th event of Fashion's Night Out had been inserted into the episode while working on the event itself. Savage commented on the filming of the episode, stating "it's really cool to be the only show to be working with these amazing organizations to be a part of a real event."[1]

Columbia University makes its 3rd appearance on the show since the third season twentieth episode, It’s a Dad, Dad, Dad, Dad World and the sixth episode of the second season, New Haven Can Wait and becomes the primary filming location for the episode.[2][3] Blake Lively and Clémence Poésy filmed their scenes outside a Carlos Miele store in the Meatpacking District at Downtown, Manhattan on July 15, 2010.[4][5]

Amanda Setton reprises her role from the first and second seasons of Gossip Girl as Penelope Shafai.[6][7] Digital Spy announced her return to the show with her character facing off against Blair Waldorf, further adding that "Blair's made a fair few enemies in her life, so it was only a matter of time until it started to come back to haunt her" and that "their roles have been reversed."[8] Melissa Fumero and Alice Callahan also reprise their roles as Blair's new minions, Zoe and Jessica from the third season.[7] Tory Burch, Alessandra Ambrosio, Hamish Bowles, Molly Sims and Robin Thicke also make cameos in the episode.[9]

The Fashion's Night Out-themed episode featured a wide array of designer looks from the show from Reem Acra, Jenny Packham, Valentino to Diane von Fürstenberg.[10] Leighton Meester wore a sparkling Valentino dress, one that Sharon Clott from MTV praised.[11][12][13] Blake Lively donned a Jenny Packham dress from her Fall 2010 collection paired with Raphael Young shoes.[4][11][12][14] Katie Cassidy was seen wearing a beige dress designed by Yigal Azrouël with leopard print denim pumps from Dolce & Gabbana while filming with Lively, who was dressed in a Robert Rodriguez top and a Missoni skirt.[15][16] Cassidy later wore a Fashion's Night Out tank with a Zadig and Voltaire shirt.[17] On July 14, 2010, a scene at Columbia showed Lively wearing Diane von Fürstenberg and Meester in Pucci, followed by a floral halter from the Erdem Spring 2010 collection and floral print skirt by Charlotte Ronson.[18][19][20] Clémence Poésy was seen wearing a Carlos Miele gown[5] and Kelly Rutherford donned a purple Reem Acra dress.[10]