Witch Hunt - S4-E6
Visible crew/equipment: Just as Abby identifies the John Doe, from the angle behind her there is a crewman in a red shirt in shot over her right shoulder. (00:34:50)
Visible crew/equipment: When Gibbs pulls the U-turn, there are markers visible on the road to indicate where to do the turn. (00:29:55)
Visible crew/equipment: At the very start as the camera pans over the sign saying base housing, the camera crew are reflected in the sign. (00:00:10)
Bete Noire - S1-E16
Visible crew/equipment: When Gerald starts to open the body bag, the film crew are reflected in the fridge door behind him. They are blurry but distinguishable by the fact the shapes move when no-one else does. (00:01:05)
Visible crew/equipment: When Tony stands up and walks over to Kate at the start, a blue tape marker is visible on the floor from where he starts walking. (00:01:35)
Visible crew/equipment: When Dr. Mallard is talking to Mr. Palmer about a "White Elephant", you can briefly see crew members on the stainless steel door on the left of the screen. They are blurry, but distinguishable. (00:23:55)
Yankee White - S1-E1
Visible crew/equipment: When Ducky tells Gibbs to go home and get some sleep, Gibbs walks over to the side and grabs some paper towels. When he does, the camera crew is reflected in the fridges opposite. (00:24:00)
Witch Hunt - S4-E6
Visible crew/equipment: When Gibbs gets the phone call in interrogation, a piece of filming equipment appears in shot on the left hand side of the screen. (00:34:10)
Witch Hunt - S4-E6
Visible crew/equipment: When Gibbs is searching the room he walks into the bathroom, turns the light on and leaves. Look in the mirror to see the reflection of the camera man's arm. (00:15:00)
Visible crew/equipment: When agent Lee walks into autopsy with Mr Palmer, the film crew is reflected in the door behind her as it closes. (00:27:45)
Singled Out - S4-E3
Visible crew/equipment: When Ziva is stretching we get a shot from in front of her and her white microphone wire is visible where her top has ridden up slightly. (00:20:30)
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