Other mistake: For secret agents, Sydney and Dixon are not very dedicated to secret identities. At several points they refer to each other by their real names in front of other people while they are under aliases. Examples include The Confession party and The Coup Las Vegas scenes.
Other mistake: When Jack logs into Lauren's e-mail account, for one, the birth dates on Lauren's IDs say 1959 and 69 (which would make her either 33 or 44). Plus you can see (possibly) real e-mails from actual crewmembers, for example at the bottom you can see "FW:Photos for Alias Ep.#315." (00:10:57)