Gossip Girl

Serena says to Lily that she found out that Lola is not her cousin but her sister. Technically Lola is both Serena's sister and cousin since she came from a union between Serena's father and aunt.

Serena calls Lola "Ivy" when she asks for her help.

In the sequence of Serena's dream. Blake Lively is lip-syncing to "Diamonds Are a Girl's Best Friend" from Gentlemen Prefer Blondes dressed as Marilyn Monroe/Lorelei Lee. During that musical number Blair Waldorf (Played by Leighton Meester) is dressed as Audrey Hepburn/Holly Golightly from "Breakfast at Tiffany's" Nate and Chuck and Dan can be seen as back-up dancers in that number as well.

This is the 100th episode.

In the scene where Serena calls Max, you can clearly see her Iphone is on the home screen and not on a call.

Even if there is an actual Pirnce Louis in Monaco, he's not the first in line to the throne, he's Princess Stéphanie's son and his family name is Ducruet. The first in line woud be Princess Caroline the her sons Andrea , her daughters Charlotte and Alexandra then Stéphanie herself, and in 6th position comes Louis then his sister Pauline

This would be Anne Archibald's first appearance since the second season episode, The Magnificent Atchibalds.

During the scene with Blair and Serena in the main Columbia Quad, the binders in Blair's hands change from green to red.

Goof: When Blair comes back to the apartment she has both shoes one when she was supposed to have only one because the other one she gave it to Louis.

When Blair was looking at the painting in the museum, we were first treated with her back view and her hands are by the side. The prince was walking towards her. Her left hand was empty and right hand was holding her bag. However, when the camera changed angle and it showed her front view, her hands were in front with both hands holding the bag.

The bandits in Prague in the end talk Hungarian, not Czech.

Although being credited Kelly Rutherford (Lily van der Woodsen) does not appear in this episode.

Guest Stars Margaret Colin and Scott Bryce played siblings Margo and Craig Montgomery on As the World Turns.

Although credited, Kelly Rutherford (Lily van der Woodsen) does not appear in this episode.

The joke that Rufus says at the Thanksgiving table is an extended variation of the popular Thanksgiving joke:

Q: What kind of music did the Pilgrims like?
A: Plymouth Rock

Nate tells Serena what happened in the episode The Handmaiden's Tale when he tried to tell her how he feels about her but ended up telling Jenny whom he thought was Serena.

Jenny mentions that Brad Alexander is an unsuitable date since he gave 6 girls from Nightingale an STD. Nightingale is the Nightingale-Bamford school, the school on which Constance-Billard was based off of.

The place of the first rehearsal for the Cotillion is the Cedar Lake Contemporary Ballet, a company based at 547 West 26th Street in New York City. The company was named one of Dance Magazine's "25 to Watch" in 2008.

It appears Horace the manager of Brooklyn Inn in the season 2 episode Chuck in Real Life is now the working with Chuck on his new hotel. Which means the Brooklyn Inn closed down despite Vanessa trying to save it. But Horace landed on his feet thanks to Chuck.

Half way through this episode Georgina is shown typing on a black Apple laptop, then is later shown typing on a silver one.