A Weak Link - S1-E22
Revealing mistake: When Gibbs and Todd are walking into the church, the camera shadow can be seen going over the seats on the left hand side. There is no-one other than Gibbs and Todd moving and the shadows are not possible from them. (00:25:00)
Answer: I hadn't seen the backdoor pilots yet but while it wasn't explicitly stated, at least onscreen, I heard somewhere Vivian got either fired from NCIS due to jeopardizing a case, got resigned from the agency, or transferred to the FBI.
Raykvega423