Penn Badgley (Dan) and Blake Lively (Serena) had known each other for years prior to the show, as they were home-schooled together when they were child actors.
When the show was criticized by the Parent Television Council for being "mind-blowingly inappropriate" and "every parent's nightmare," those exact phrases were used in the show's promotional posters.
The CW did not want Ed Westwick to play Chuck Bass, insisting that he looked "more like a serial killer than a romantic lead."
The Empire Hotel that Chuck owned is a real hotel. After fans swarmed the hotel, the bar at The Empire started serving Gossip Girl-themed cocktails, including an "XOXO" cocktail with secret ingredients that they'll never tell.