Lena Olin was unavailable, at the time of production, when picture inserts were needed of her, for the picture found by Nadia in this episode, of Irina holding a baby [her niece]. At the last minute, Angela DeAwn [Nadia], offered to step in to play the part of Irina in the picture.
Kiera/Meghan asks Vaughn if he works for MI-5, but MI-5 is Britain's counterintelligence service, and doesn't operate outside of Britain. MI-6 is foreign intelligence.
The second picture Nadia goes through is a B&W of Jennifer Garner in glasses with her real life sister, Susannah on the right. In the middle is supposed to be Irina.
The language locals speak in the hospital in Montenegro is Russian, but the language spoken in Montenegro is Serbian.
In the Montenegran hospital all the light switches are American. Only American light switches flick up to turn on. Montenegran ones would flick down to switch on.
The newly introduced "Baden-Liga" might be a reference to the already known "Badenweiler" (location of the later destroyed plant and inhaler) from season one's episode "Doppelgänger"
When Sydney breaks into the server, she places the laser watch she used into her pocket, as it overheated. However, when she is captured, it is back on her wrist and she uses it to burn through her restraints and escape.
Mitch is 14 months old in this episode.
In the parking lot where Sydney chases Martin, which is supposed to be in Europe, there are several cars which can only be bought in America, such as the Cadillac CTS, the Chevy Trailblazer, and the Infiniti FX45.
In Spain, cars have plates both in the front and in the back. Martin's Mercedes would have been stopped by the Guardia Civil for not carrying the front one.
When Weiss and Nadia are talking at the party, Nadia takes a sip of her wine glass. You can clearly see that the glass is almost empty. When we see her the next time with her glass, it's almost full.
When Sydney's breaking into the safe she never removes the stuff the used to fake a palm print from the screen.
The ECG when Jack questions Nadia is obviously fake. The dot drawing the graph should have a constant x-axis velocity. Instead it stops horizontally, while drawing the heartbeat 'zigzag'.
Goof: While Vaughn speaks with Sydney through the laser microphone he sweeps over some windows. How can he still speak with Sydney when he isn't aiming at her?
In the scene where Sydney is crawling through the vent in the museum the footage was, in fact, unused footage from the Season 1 two-parter "The Box" Parts One and Two.
Sydney's cover for APO is that she works in a bank, the same cover she had for SD-6.
Marshall drives a Mini Cooper.
Another mistake: In Brazil, all public telephones are blue, but in this episode, they show a black one. The clothes Vaughn, Nadia, Sydney and Jack are using aren't used by Brazilians. They are a total misconception about the way they dress. And that square doesn't look like a Brazilian one.
Marshall says there was an earthquake in Brazil, in 1944, which was the reason why the tunnel was reinforced. However, there was no earthquake in Brazil that year. There was, however, one in San Juan, Argentina which measured 7.4 on the Richter scale.
Goof: Sydney steals the sword from London, but the police sirens we hear are French. Obviously a generic European siren by the sound effects dept! Plus the Police car used by Jack Bristow is straight out of the 1980s - Hardly fitting for a 2005 cover.