Once a Hero - S4-E8
Revealing mistake: When we see Ziva having a close up look at the dead girl, the dead girl's eyes twitch and move slightly. (00:09:20)
Once a Hero - S4-E8
Revealing mistake: When Ducky and Gibbs are in the morgue examining the body of the girl found in the hotel, the camera cuts for a few seconds to the girl lying on the slab. During that shot, you can see her neck moving to her pulse (just after Ducky says, "There's some bruising on the sternum"). (00:19:10)
Once a Hero - S4-E8
Revealing mistake: When Ducky opens the fridge door containing the suspected killer, the dead body's eye twitches. (00:21:00)
Chosen answer: It is never stated, however she must have been there several years if she is on presidential detail.