Continuity mistake: When Abby is talking to Gibbs about getting a tattoo, he goes from looking at her computer screen to her in between shots. There's a straight cut, so there was no time for him to turn his head. (00:06:55)
Continuity mistake: When Gibbs drops the nails on the food carton, the position of the nails goes from spread out to grouped together instantly. (00:19:50)
Continuity mistake: When Sharif calls Gibbs to gloat, when Sharif ends the call, the shot cuts to Gibbs closing his cell phone, shot cuts to McGee and Col. Mann, when it cuts back to Gibbs, he is closing his phone again. We can even hear the phone close both times. (00:33:10)
Continuity mistake: During the scene where Gibbs chases Shariff into the railway station restroom, Gibbs' position on The Wall changes, his gun hand passes the corner of The Wall at least three times. Also as he starts to fall to the floor, the long shot from low angle close to the urinals shows Gibbs holding the gun with both hands and they are moving to his right, his left shoulder going into he wall. At the cut, the gun is in his right hand only and moving across his body to the left and his right shoulder is now going into The Wall. The shot cuts to Shariff, who has moved about a foot to his right during the cut, then cuts back to both Gibbs and Shariff, Shariff has returned to his original position and the gun has moved to Gibbs left hand, although we don't really see the gun until he falls and Shariff picks it up, thus ruling out the possibility of the gun being dropped before he falls. (We do hear the gun hit the floor as he falls.) (00:40:10)
Continuity mistake: In the Episode "Sharif Returns" When Ducky shows Gibbs the eye in the gladd vial, it alternates between being completely submerged in the fluid to sticking out the top.
Continuity mistake: When Gibbs is at the batting cage with Col. Mann, he raises his bat, ready to swing. In the next shot, his arms are down by his side and he raises the bat again. (00:02:30)
Continuity mistake: Tony removes his cigar from his mouth using his right hand. Camera changes and now he has his torch in his right hand. (00:24:30)
Cover Story - S4-E20
Continuity mistake: The way Ducky holds the dictaphone changes between shots. (00:13:45)
Cover Story - S4-E20
Continuity mistake: Just as Ducky is finishing reading the letter out loud to Gibbs, he has the letter in both hands. Camera cuts and now he is holding it in one hand. The Dictaphone also appears on the table instead of in his hand. (00:13:50)
Cover Story - S4-E20
Continuity mistake: When Todd is arrested, he has his hands behind his head. Camera cuts and now they are shoulder height. (00:28:00)
Cover Story - S4-E20
Continuity mistake: When McGee is free-writing, the stuff he has styped changes between the two close ups. While the words remain the same, the spelling and punctuation changes. "Was" becomes "Wsa", "Gat" becomes "gat", "desser" becomes "des" and "Bang" becomes "bang". (00:33:40)
Cover Story - S4-E20
Continuity mistake: When McGee is writing, we see he is working on a new paragraph. Camera cuts away for 6 seconds and then cuts back and now he is already halfway through the third line of that paragraph despite there not being enough time or enough pings of the typewriter resetting. (00:33:50)
Cover Story - S4-E20
Continuity mistake: We see Abby's phone lit up and ringing. Camera cuts and now it's no longer illuminated but still ringing. (00:37:00)
Continuity mistake: When Abby chucks the polystyrene in the box, its position changes between shots. (00:18:10)
Chosen answer: It is never stated, however she must have been there several years if she is on presidential detail.