Continuity mistake: Vance checks on Langer's pulse and uses 4 fingers. Camera changes and he is using 2. (00:37:20)
Continuity mistake: When Vance shows Gibbs the access card belonging to their dead petty officer, the position of his hand on the card changes between shots. (00:38:35)
Chosen answer: It is never stated, however she must have been there several years if she is on presidential detail.