Day 5: 7:00 A.M.-8:00 A.M. - S5-E1
Continuity mistake: Season 5 Episode 1 Hour 07:00 A.M. The bad guy goes for Chloe and starts running at full speed close to the door (15 steps?) at 00:17:24. After 9 seconds "running," he barely is at the door. (00:17:25)
Day 5: 9:00 A.M.-10:00 A.M. - S5-E3
Continuity mistake: During Episode 3 of Season 5, the terrorists take Derek in front of live television. When the terrorists force him on his knees, you can see a splatter of blood on the floor from the body of the last victim that was shot there. As time is running out, another shot of Derek being held by the terrorists is shown, and the mere splatter of blood that had been near his knees is now a noticeably big pool of blood. Nobody has harmed Derek yet, and there are no signs that he is bleeding. So where did all that blood come from?
Day 5: 11:00 A.M.-12:00 P.M. - S5-E5
Continuity mistake: Season five, 5th hour. Lynn knows about the four people who knew Jack was still alive, he mentions their names and talks to Jack about it. Yet when they are told Tony wants to speak with Jack, Lynn looks completely puzzled and Jack tells him that he knew Tony. Minutes earlier Lynn already knew that.
Day 5: 1:00 PM - 2:00 PM - S5-E7
Continuity mistake: In the "Previously on." montage, Ivan Erwich tells Walt Cummings "Your country is about to pay a very steep price for betraying us." But at the end of the previous episode, Erwich never says "for betraying us."
Day 5: 1:00 PM - 2:00 PM - S5-E7
Continuity mistake: When Spenser tells Jack that someone else is in Rossler's penthouse, he says "In the bedroom to your right," but Jack then glances to his left.
Day 5: 5:00 PM - 6:00 PM - S5-E11
Continuity mistake: When Agent Aaron Pierce steps out of the helicopter, the right half of his face is severely wounded, with lots of blood and a bandage on it. 12 minutes later, when he is back in the Presidential house, he's talking with Miss. Logan and his face is completely clean, with not a single scratch or sign of wounds on his right half of the face. (00:12:55 - 00:25:00)
Day 5: 9:00 PM - 10:00 PM - S5-E15
Continuity mistake: Season 5 - 9pm-10pm, at 9:41pm. - Technical weapon error. When Jack takes the Federal Marshal's' Glock pistol, in an effort to add drama, he holds the pistol in his right hand and cocks it with his left hand by grabbing the slide, pulling it back, and releasing it to chamber another round. However, after he does this, the camera zooms in on the gun as it is pointed at Colette's' head and you can see that the slide is still back on the gun and NOT capable of firing at all.
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 ★