Continuity mistake: At about 2:15am, when Jack's talking to Nina about the passenger list on the plane, we see a shot of Jack in the top left, and Nina in the top right. Because it's real time they're both meant to match up - we're watching them both at the same time. In each shot we can see the back of the other's head, but while Jack is looking down and around in the left-hand shot, in the right-hand shot his head is staying perfectly still. (00:15:51)
Visible crew/equipment: As Kim runs over to her friend at the end, a camera shadow can be seen on her arm. (00:41:00)
Answer: According to Jack in season 5, Nina was "deep cover" before the pair ever met, so it's safe to assume she was recruited before she joined CTU. As for what her primary mission was, who knows? Perhaps it was to gather sensitive intel and pass it on to her superiors. Given that she worked for an intelligence agency, it's not a stretch. Or perhaps we may find out in season seven.
Cubs Fan ★