Writer:	Alex Kurtzman, Roberto Orci
Director:	Ken Olin
Star:	Lena Olin (Irina Derevko),  David Anders (Sark),  Bradley Cooper (William 'Will' D. Tippin),  Victor Garber (Jonathan 'Jack' Donahue Bristow),  Michael Vartan (Michael C. Vaughn),  Ron Rifkin (Arvin Sloane),  Carl Lumbly (Marcus R. Dixon),  Merrin Dungey (Francine 'Francie' Calfo),  Jennifer Garner (Sydney Anne Bristow),  Kevin Weisman (Marshall J. Flinkman)
Recurring Role:	Greg Grunberg (Agent Eric Weiss),  Terry O'Quinn (Kendall),  Ira Heiden (Techie #4)
Guest Star:	Eric Betts (Guard #2),  Lina So (Cocktail Waitress),  Jeanette Goldstein (Medical Bay Technician),  Ethan Hawke (Lennox),  Olivia d'Abo (Emma Wallace),  Terry Urdang (Techie #5),  Joel Guggenheim (Techie #3),  Michael Yavnieli (Techie #2),  Steve Heinze (Ranking Agent),  Bru Muller (Negotiator),  Michael Mastro (Arden Jezek),  Constance Brenneman (Christine Phillips)

Music from this episode includes:
"Moving In Stereo" by the Cars
"God Put a Smile Upon Your Face" by Coldplay (edit) This episode was originally slated to air before "Phase One", after the Super Bowl, presumably using different footage with SD-6 still active. You can tell, the characters motivation's are still "gung ho", not consistant with the destruction of SD-6, and none of "Phase One"'s loose ends (Marcus, Marshall, Irina, Sloane, Sydney leaving the CIA, Et al) are tied up, with the exception of the genetic double. (edit) Although credited Bradley Cooper, Carl Lumbly, Kevin Weisman, David Anders and Lena Olin are all absent from this episode and Ron Rifkin only appears briefly in one scene. (edit) For the second episode in a row the standard opening titles were not used. (edit)

(After SD-6’s fall)
Sydney: I was thinking... (with a smug smile) now I can actually go to the CIA through the front door. (edit) (Sydney walks into the safe house and finds it trashed, and Agent Lennox drunk)
Agent Lennox: Beware of the grieving man and his bottle. (edit) Sydney: How is this possible without obvious scarring?
Jack: The procedure isn't surgical. A patient's genetic code is altered to reshape their physical attributes.
Sydney: Is it reversible?
Jack: It's unclear. It only works on people of a certain genetic disposition and the recipient must be induced into a comatose state for several days while their cells regenerate. The data indicates the only way to distinguish the real person from the double is by an ocular scan. A flaw in the iris was deliberately built into the procedure to tell them apart. (edit) Jack: (to Sydney) We've decrypted the specs on Project Helix that you and Vaughn obtained. The data describes a breakthrough in next-generation molecular gene therapy. It refers to a new procedure whereby a patient's face and body are reshaped to identically resemble someone else. Agent Lennox was the first test subject to be doubled. (edit) Lennox: Emma used to say that she had spent so much of her life pretending to be other people that she was afraid she might disappear. And I have been sitting here trying to remember all her aliases and you're right. It's hard to keep track.
Sydney: I lost my fiancé last year and I know we're trained to compartmentalize things that hurt too much but I still haven't been able to do that. As hard as it is, I would rather feel it than to not feel anything. (edit)

Number 47: Agent Lennox was being held in room 47. (edit) When Lennox#2 calls in to the CIA as he's racing toward the railway yard, he says he was captured in Concho Caya, when in fact the place is called Cayo Concha (the writers could have included this slip intentionally to suggest that the character isn't telling the truth, but that conclusion is never drawn by the CIA). (edit) The blonde german officer 'Klaus', that tries to negotiate with the explosive-rigged CIA-Agent in Berlin does not know how to speak proper german, but is sent to negotiate in that language. (edit) The german police car shown in the scenes is white. However german police cars are usually green-white. Also german police uses cars from german manufacturers but the black police car shown is a Chrysler with an american blue light on it. (edit)

Olivia d'Abo, who played "Emma Wallace" in the episode also played another Wallace, Nicole Wallace, as a guest star character on "Law and Order: Criminal Intent". (edit) Audio/Video: "Moving in Stereo" playing as Sydney exits the pool in slow motion.
The scene where Sydney exits the pool with "Moving in Stereo" in the background is a tip of the hat to the famous scene in Fast Times at Ridgemont High where Phoebe Cates exits the pool in Judge Reinhold's fantasy. (edit)