First episode that does not end with a comment from Gossip Girl.
This is the first episode to feature recurring character, Vanessa (Jessica Szohr).
The picture of Serena for her ad on the Gossip Girl site was from the second episode, The Wild Brunch (2007), when Blair and Nate had come into the hotel room Serena was in.
This is the first episode to feature Anne Archibald (Francie Swift) as a recurring character.
When Dan's ex mentions "perogies at Veselka" she is referring to eating perogies, an Eastern European dumpling. Veselka is a restaurant on 2nd Avenue and 9th Street in the East Village in Manhattan.