Character mistake: When Kate mentions James Bond, and DiNozzo lists the actors who have played him, he forgets Timothy Dalton. As a self-proclaimed film buff, that's not a mistake he would make.
Character mistake: When Gibbs shows Major Dorden his badge, his ID card is upside down. (00:06:00)
Character mistake: Dr. Ducky mentions that the inventor of the guillotine in France was Dr. Joseph-Ignace Guillotin, but it was actually Dr. Antoine Louis.
Character mistake: At the start, Kort takes the gun from one guy and uses it. He then places it at the second man's body without wiping it for prints. When he swaps his gun though, he wipes it for prints. Why didn't he wipe the first gun he used? (00:00:50)
Character mistake: In the scene, where Jeanne tells Tony that he never said he loves her, besides after sexual activities. This is not true. In episode 15 "Friends and lovers" Tony ends a phone call saying "I love you."
Character mistake: When Gibbs tells William Danforth that the body in autopsy isn't his son, he says, "Not according to AFIS." AFIS is the fingerprint database; since the body was identified using DNA, Gibbs meant to say "CODIS." (00:13:50)
Under Covers - S3-E8
Character mistake: In one scene, Jenny refers to "the former Czech Republic." That is the state's current name; it was formerly a part of Czechoslovakia.
The Truth Is Out There - S1-E17
Character mistake: Gibbs and Ducky are in Autopsy, with Ducky describing lower-leg injuries of a deceased Petty Officer. The two bones in the lower leg are the tibia and the fibula; however, Ducky, a doctor with decades of experience, referred to the injuries as fractures of the "tibia" and "fibia." (00:13:05)
Character mistake: In isolation, Tony mentions John Travolta and says that he's known as the "king of cool." That nickname referred to Steve McQueen, not Travolta. (00:15:10)
Yankee White - S1-E1
Character mistake: The uniform/costume that Major Tim Kerry, a Marine Military Aide to the President, is wearing, includes a Service Aiguillette made of 4 loops of round gold wire and scarlet cord. This aiguillette is worn by a Marine serving as an Aide or in other positions for a 4 Star General. A military aide to the President would wear 4 loops, all gold (as seen being worn by Commander Ray Trapp). (00:29:00)
Broken Arrow - S8-E7
Character mistake: Ducky is a native Scotsman and refers to Dartmouth as being in "Devonshire" As any Brit would know, it's simply Devon or County Devon. (00:05:00)
Character mistake: When Gibbs first looks at the victim's body and sees his rank, he incorrectly refers to him as a Lieutenant when the rank is for a Captain.
Lost & Found - S5-E9
Character mistake: We see McGee using his computer where the word violators is spelled violaters on the NCIS search form. (00:23:15)
In the Dark - S4-E22
Character mistake: On the message board visible in the background when the team is discussing Wong, the word "Artillery" is misspelled "Artillary". (00:18:20)
Bete Noire - S1-E16
Character mistake: Ari tells Ducky and Gerald that if they lie or he suspects them of lying, he will shoot them in a ball-and-socket joint. Ari later shoots Gerald in the shoulder and mentions that next time it would be his knee. The knee is not a ball-and-socket joint. It is a hinge joint. The only other ball-and-socket joint in the human body is located in the hip. Ari is an educated Doctor and should know the difference. (00:24:00)
Lost at Sea - S10-E4
Character mistake: During the interrogation of Petty Officer Sparks, JAG Officer Lieutenant Nora Patel says "Lieutenant Sparks has a right to legal counsel." (00:21:50)
Character mistake: We see McGee searching on his computer and the phrase "violaters will be prosecuted" is seen below the search bar. The word violators is misspelled. (00:14:50)
Character mistake: Ducky states that the Romans believed that the vein of 4th finger on the left hand ran directly to the heart, thus, logically, it was the "ring" finger. However, there is no evidence that the belief originated with the Romans, nor that the 4th finger has a special vein...the fingers in the hand have a similar vein structure.
