A Man Walks Into a Bar... - S8-E14
Visible crew/equipment: While Gibbs and Tony are in the galley interrogating the two members of the crew because they worked closely with Commander Reynolds, when Gibbs asks them if the gun looks familia, the boom mic dips into view at the top of the screen. (00:32:40)
Visible crew/equipment: When Gibbs tells Gail Walsh that they're keeping Jerry at NCIS, Gail replies, "Only on the condition that you keep me apprised of any new information," and in the next shot from behind Gail, a crew member (presumably the boom operator) wearing a black shirt and white pants is visible at the left side of the screen. (00:25:10)
Visible crew/equipment: While Gibbs and Ziva are interviewing the teacher in the classroom at Quantico, in the wide shot facing Ziva as she confirms the number of students, there are two red tape marks on the floor beside the two back legs of her chair. (00:05:20)
Visible crew/equipment: When Gibbs tells the team to gear up because there's some kind of gas leak at Quantico, at the start of the first shot at the high school, the blue tape mark is visible on the floor between McGee's feet. (00:03:05)
Out of the Frying Pan - S8-E18
Continuity mistake: Vance slams the axe on the table and through a picture of the victim. However, when Vance removes the axe a minute later, the axe is through a different part of the picture. The 1st time the axe goes through the neck/shoulders of the man in the picture but when removed it's in the forehead. (00:29:50)
Other mistake: McGee says that Jancy got into her cab at 12:37am and arrived at her destination at 12:55. That's 18 minutes for the taxi to drive "over 20 miles away" Hardly likely given traffic. (00:29:00)
Suggested correction: You missed the point of what he said. The cab ride ends at Gilroy's address, which is 20 miles from Travis Wooten's home. But the ride didn't start at Wooten's home, it started at Feeney's Billiard Club. They don't make any mention how many miles the ride was.
Continuity mistake: Right at the end, the dying Poloma reaches up and touches her brother's right cheek. Her bloody fingers leave a trail behind. This disappears in the next shot when Alejandro turns his head to look at Gibbs.