Continuity mistake: When the mannequin is hit it's on the double yellow lines with another mannequin stood on the lines behind the first one. When the 4x4 drives off, the second mannequin has moved on its own from the double yellow line to the side with the other 2 upright male mannequins. (00:00:45)
Continuity mistake: At the start, Otto hits the mannequin straight forward. Camera changes and now the mannequin is to the side of the 4x4. After the mannequin is hit, the woman looks out of her side window to look at it. However when we see the 4x4 drive off the mannequin is now on the opposite side. (00:00:50)
Once a Hero - S4-E8
Audio problem: When the director is working out the letters on The Wall in the video feed her mouth doesn't move for the last L but her voice is heard. (00:38:20)
Once a Hero - S4-E8
Continuity mistake: When DiNozzo is resting at his desk, he has he feet crossed with his left foot on top of his right foot. When the shot changes his right foot is now on top. His hands have also gone from clenched to unclenched in the same shots. (00:20:25)
Once a Hero - S4-E8
Revealing mistake: When we see Ziva having a close up look at the dead girl, the dead girl's eyes twitch and move slightly. (00:09:20)
Once a Hero - S4-E8
Continuity mistake: The way Gibbs holds his ID out to the maintenance man changes between shots. In the first shot he has 2 fingers inside the ID in the second shot just his thumb is inside the ID. (00:07:40)
Once a Hero - S4-E8
Other mistake: Ducky states that the Bronze Star was for Valor. However, the bronze V that signifies the star was for Valor is not present. There is no way Ducky could know it was for Valor. (00:05:20)
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)
Continuity mistake: When McGee starts filming the fight, the women are on the floor. However when he shows the video to Abby they are stood up at the start. (00:19:00)
Singled Out - S4-E3
Continuity mistake: When McGee spots the tyre marks of the unknown car, he is holding the markers in his left hand out to the side. Camera changes and now he is holding them two handed in front of his chest. (00:09:30)
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