EXCLUSIVE: Gossip Girl - Behind The Scenes; Tyra Banks & Hillary Duff Guest Star

The cast and crew of Gossip Girl took over midtown this week and welcomed Tyra Banks and Hilary Duff to the fold.

The show filmed scenes Wednesday of a fictitious movie premiere for "Fleur" at the Ziegfeld Theater, creating a strange mix as real paparazzi and fans mingled with extras dressed as paparazzi and fans. According to security, Penn Badgley, Ed Westwick, Blake Lively and guest co-stars Tyra Banks and Hilary Duff shot interiors during the day and exterior red carpet scenes Wednesday night until after midnight.

In the scene filming Wednesday and Thursday night, which airs October 5, Tyra Banks plays an actress named Ursula Nyquist who gets into a fight with Serena (Blake Lively) at a film premiere. Duff's character, Olivia Burke who takes a break from acting and returns to college (NYU), co-stars with Banks in the movie.

For the most part Wednesday, stars kept out of public view. "Security is being a bunch of (bleeps) today," a grip told RadarOnline.com  "They're really being pushy." Briefly around noon, flanked by two beefy security guards, Lively dashed from her trailer to another in a blur of blond hair, wearing Wayfarers and sporting dangerously skimpy short-shorts. Ed Westwick, noticeably bulked up, was spotted earlier outside his trailer blabbing away on his cell and wearing a porkpie hat.

Duff, also wearing a porkpie hat (new Gossip Girl fashion accessory?) seemed to fit right in with the cast and looked relaxed while drinking a diet coke and carrying what looks to be a script. She joked around with Badgley outside trailers and her hockey boyfriend Mike Comrie stopped by the set for lunch.

On her way to the set shortly before midnight, RadarOnline.com nearly ran over Leighton Meester, who was smiling and friendly with fans. Looking drop-dead gorgeous in a silky yellow dress, we completely forgot to ask her about the sex tape she denied existed. Shame.

The set was relaxed and casual Wednesday, but Tuesday seemed a little tense. Sources tell RadarOnline.com that tensions were high Tuesday on the set in Brooklyn as Taylor Momsen screamed at her makeup artist (perhaps the new hair and makeup change to rocker chick chic isn't working for the show?). Chace Crawford, however, was the picture of cool as he wandered from trailer to trailer, smiling and looking casual, dressed in his school uniform as he waited patiently for his scenes.