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)
Cover Story - S4-E20
Revealing mistake: When Ducky is holding the dictaphone, it is off as the display is blank. (00:13:45)
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)
Revealing mistake: During season 4 the same television clip of President Bush and VP Cheney disembarking Air Force One is used on the background television in the squad room. In some cases the clip is running and not in unison, on three of the televisions in the same scene from shot to shot.
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)
In the Dark - S4-E22
Revealing mistake: When Tony is telling Gibbs & Ducky that Abby got a hit on the dead sailor's fingerprints, Gibbs takes the file from Tony; the camera shows the file, which appears to be a legitimate profile sheet, but in the comments section, is the script that Tony just read aloud. (00:07:36)
Chosen answer: It is never stated, however she must have been there several years if she is on presidential detail.