Visible crew/equipment: When talking to Ziva in the car, Eli's glasses reflect a light screen in his glasses. (00:29:10)
Visible crew/equipment: When Ziva and Eli are talking, a camera crew can be seen in Eli's glasses. (00:30:10)
Revealing mistake: When Ziva is hugging her dead father, you can see him breathing. (00:36:00)
Continuity mistake: Abby says that McGee is the most helpful person with clipboards. When she does, the position of the clipboard in her arms is constantly changing between instant cuts. (00:03:30)
Continuity mistake: When we first see young Abby, the way she's holding her bear changes between shots. (00:04:50)
Continuity mistake: In the evidence locker, Ziva opens a folder and the white notepad is on the left-hand side. Camera changes to behind her, and now the white pad is on the right. (00:26:40)
Factual error: There is a flashback scene in this episode, where a young, dejected Abby Sciuto is walking along railroad tracks after failing to give the bear back to Ricki. This scene starts with a shot of the railroad tracks, then pans up to Abby. It can be seen that the rails are laid on concrete sleepers, with modern steel clips holding the rails to the sleepers. Given that the flashback appears to take place when she was at least a couple of decades younger (i.e. the mid-1990s), such modern methods of construction wouldn't have been used. A period-accurate railroad track would have wooden sleepers, spikes and lighter rail. As such, it's obvious that the producers just went to the nearest railroad tracks and filmed the scene there.
Continuity mistake: We see a close-up of Kevin's poster that Ziva is holding. In the close-up, she is holding the poster on the right-hand side. When the shot changes to a wider shot showing Ziva and Tony, Ziva is no longer holding the poster on the right-hand side, but is now holding it on the bottom. (00:04:40)
Visible crew/equipment: While at Gitmo, Sergeant Spooner is attacked by a detainee, and when Tony joins in the tussle the gun is fired. It then cuts to the tented Global Courier van, and the pink tape mark is visible on the ground behind the van. (00:35:50)
Continuity mistake: When Gibbs speaks to the Metro detective, the way the officer next to him holds the sheet of paper on his notepad changes between shots. (00:06:50)
Continuity mistake: When Gibbs is planing wood in his basement for the first time, pay close attention to his tool. It has no blade in it at all. (00:11:50)
Continuity mistake: When Tony is on a video call with Ziva and McGee, in the shot of Tony holding out the phone, there is no-one in the pool by the orange towel. When we see the same shot from the video call in NCIS, two people have appeared by the orange towel with no time to move into position. (00:16:30)
Continuity mistake: When Tony is holding out the phone to the ladies walking past him, you can see on the phone's screen Ziva and McGee, who are stood in front of a fixed screen at NCIS. In this shot of them, you can see part of the orange wall of the office. Gibbs then walks in next to McGee. When Tony realises Gibbs is there, the orange section is no longer visible, meaning the camera has changed position. Even if McGee, Gibbs, and Ziva had moved, the orange wall should still be visible since the camera is fixed. (00:16:50)
Chosen answer: It is never stated, however she must have been there several years if she is on presidential detail.