In the car with Ziva, Tony is wearing his seat belt, not wearing his seat belt, and again wearing his seat belt.
Armand Assante's character's nickname is "la grenouille", which is French for the frog. Everyone pronounces this as "gren-wie", but not every combination of the letters o-u-i is pronounced like the word "oui" (yes). The proper pronunciation would be "gren-ooj".
The nation of Zaire is mentioned in this episode. Zaire has not existed since 1997, it is now the Democratic Republic of the Congo. The writers may not have been aware of this change, or chose to ignore it for clarity that the team was going deep into Africa.
When David and McGee chase Harrow up the steps at L'Enfant Plaza, a skyscraper is seen in the background in two shots. There are no skyscrapers in Washington DC due to architectural height restrictions in the District of Columbia.
At 28:10 we see an overhead map shot of the airport to be the drop off point for Ares. In locating the stated " 45 26'19"N 71 41' 29w " on Google maps, this is Sherbrooke Airport (YSC) actually in Quebec. However, the picture shown to the audience is of the Augusta State Airport 167 miles SE of " 45 26'19"N 71 41' 29w "
Agents David and McGee are "made" by Harrow near a café on "35th St." (as stated later). After the agents chase Harrow a short ways, he has a heart attack at the top of stairs that McGee identifies as L'Enfant Plaza when he calls for medical assistance (this appears to have been shot on the Hope Street side of the Central Library in Downtown Los Angeles). However, the nearest 35th St to L'Enfant Plaza (D and 10th St SW) is 35th St NW, a 30-40 block distance that a man in Harrow's condition wouldn't have made.
In this episode, the character Rene/La Grenouille states that the Cognac "L'Esprit de Courvoisier" was first drunk by Napoleon at his coronation in 1802. Napoleon Bonaparte had effectively taken power in France in 1799 as "First Consol", but he only assumed the title of "Emperor of the French" as 'Napoleon I' - and held his - coronation - in 1804.
While observing La Grenouille's plane, McGee states takeoff time as 24:00 (twenty-four hundred). In military time, the latest time is 23:59, followed by 00:00 (zero hundred.) While McGee may make such a mistake, Gibbs, having been a Marine, would have known better and would have corrected Tim.
While Ziva is assisting Ducky with his disguise to look like Charles Harrow, McGee is trying to get his attention and calls him "Dunky".
Abby incorrectly calls the computer desktop wallpaper that she and McGee are looking at a screen saver.
Abby says about one of Harrow's hard drive arrays, "...a terabyte of storage... That's a thousand gigabytes of fun!" McGee replies, "No, to be accurate, it's 1,024 gigabytes of fun". While most other computer components (like memory) use binary powers (2^10 = 1,024) for capacities, hard drives use decimal powers (1 terabyte = 1,000,000,000,000 bytes). Although even experienced computer users may make this mistake, "McGeek" would know this.