John G. Connolly who plays the German CT head, Keller, has an injury to his right eye (looks like a couple capillaries popped) in the scenes that take place in the beginning and the end - the black tie parties. The scenes in between show him without the blemish. He obviously had the injury during the day they filmed both scenes which breaks continuity a bit.
When Kim Brown goes out to board her old flame's private jet, it is a Gulfstream IV that is parked on the apron outside the terminal. The next shot of the now airborne private jet is of a Learjet, not a Gulfstream.
The beginning starts off with Keller and the members of the team at his casino talking about the game. Keller has a massive blood vessel rupture in his right eye. During the next scene in the conference/meeting room, his eyes are both clear. Then, in the last scene, when Keller is speaking with the Unit in his casino supposedly a day later, his right eyes is red with blood.
Often the map of the subway network of Hamburg Germany is shown, however the company that runs the subway is called HVV and not VVH as shown on the maps. The logo seems to be mirror-inverted - yet the subway map itself is correct showing the right map of the different underground and overground train systems.
The members of The Unit say "I repeat" on their comm systems a number of times. Since "repeat" is an artillery command to fire upon previously given coordinates, Army personnel always say "I say again" instead of "I repeat".
Although the team members are located in Hamburg, Germany, none of the passing cars are mounted with German license plates. German cars have white plates, both at the front and at the back. Most cars in passing by have white plates in the front and yellow plates in the back making them French and the 75 ending tells us the cars are registered in Paris. One passing (local) taxi is even mounted with Spanish looking plates. The subway stops shown aren't in Hamburg, although the subway stop names are existing in the Hamburg public transport system.