The second camera Sydney "fires" from her lip gloss gun is visible in the ceiling before she "fires" it.
During the initial shoot out where Hater is gunned down in his car, the gunman walk away, and Hater's driver side window is intact. However, as the gunmen drive by, they throw a grenade through the now missing window.
Irina has a blanket and pillow in her cell when she comes back to the CIA Rotunda. However later on in Passage: Part 1 Irina asks for some comfort in the shape of a blanket and a pillow.
After disabling the firewall, Alias provides Dixon a dummy IP address to give to SD-6. Although it's a dummy address, that only means it's not really the intended server; it is supposed to be operational and lead SD-6 to a different server. The address that she cites, 259.10.3.179, cannot possibly exist. Each number in an IP address has a maximum value of 255. (Also, an actual usable address of an individual computer cannot start with a number higher than 223 for other reasons.)
When in Vienna the shot establishing the scene does not show Vienna, but Prague. Also, some yellow, four-sided traffic-lights are shown. Traffic lights in Vienna are painted black or dark Grey, but never yellow. Interestingly, the license plates on the cars driven by the terrorists and the victim are authentic (the Viennese coat of arms might be mistaken for a Swiss flag, but is in fact represented correctly).
Agent Sydney Bristow goes to Buenos Aires, Argentina, seeking a former KGB psychologist. The footage shows a villa surrounded by low hills, which Buenos Aires doesn't have. The whole city of Buenos Aires is a plain terrain.