Under Covers - S3-E8
Continuity mistake: When Jenny joins Gibbs and Fornell in MTAC, she puts on a headset and lowers the microphone. In the next shot, she secures the headset and lowers the microphone a second time. (00:28:45)
Under Covers - S3-E8
Continuity mistake: When the assassin is getting ready to take Ziva to her room, he has a jacket covering his silenced pistol. However the jacket is constantly moving in relation to the end of the silencer. (00:35:00)
Under Covers - S3-E8
Character mistake: In one scene, Jenny refers to "the former Czech Republic." That is the state's current name; it was formerly a part of Czechoslovakia.
Under Covers - S3-E8
Continuity mistake: In S1 E15 "Enigma", about 30 minutes in, Gibbs takes out his flask and the engraving is "For Good Luck, Your Loving" with the bullet on it. At the end of this episode it's engraved with "Jethro, For Good Luck Love Shannon and Kelly".
Chosen answer: It is never stated, however she must have been there several years if she is on presidential detail.