On the Cargo Ship level, a radio can be heard talking about the East Coast blackout. However, the blackout had not occurred yet in the game and occurs in a later level.
In the mission 'Hokkaido', Redding mentions to Fisher that Milan Nedich's real name is 'Milos Nowak' and is a wanted war criminal from the Bosnian war. Because in the Bosnian alphabet there is no 'w', it should be 'Novak' instead. Nowak is actually the Polish version of that surname.
The navy captain has anchors on his rank insignia, when he should have stars. Also, his pants are black when they should be white.
The navy captain is wearing his service uniform underway on a warship, when he should be wearing coveralls or wash khakis.
The USS Clarence E. Walsh is flying the U.S. flag from the fantail while underway. This is only done when at a pier or anchored.
The EA-6 is crewed by 4 not 2.
Some of the Korean signs in the Seoul level are upside down and reversed.
The North Korean trucks have the steering wheel on the right, when they should be on the left.
In the battery level, the map of Korea on the monitors is reversed.
In one of the WNM broadcasts, "defense" is spelled the British way.
Grammar and spelling mistakes in subtitles.
In the bank vault scene, Turtle says 'Thing-a-bob' but the dialog says 'Do-hickey'.
Mr. Fisher's gear has glowing devices such as the night vision goggles and radio which would defeat his hiding in darkness.
A couple of hostile NPCs are talking about motion-sensing lights as if they are new technology, despite the technology being around for many years.
The telemetric pick needs a few seconds to sync with the lockpicking of the Player. It does not need to do so for the last pin, even though it should since it isn't doing any different action than what it is doing with the other pins.
Mr. Fisher's OCP can be used to disable electronic circuitry. It also disables lights, although there is no circuitry in a light bulb that can be disabled.
The navy captain is wearing the "salt and pepper" uniform in 2007, when it was discontinued in the 1980s.
In the North Korea Battery level, there is a Japanese trash can.
In the Seoul level, a building has a North American-style fire alarm.
Even just knocking a target out is equivalent to eliminating them as far as missions go, even though it would leave them alive to so more objectionable deeds.
Otomo refers to the Japanese constitution as being from 1946 when it actually from 1947.
Sam and Grim say that the Gulf War happened in 1989; it happened in 1991.
When Mr. Fisher is aboard the Maria Narcissa, Mr. Redding states that Mr. Fisher needs to activate the bilge to clear some flooded compartments. A bilge is the bottom of a ship's hull; what Mr. Fisher needs to activate is a bilge pump.
Several characters (Masson, Lambert, Grimsdottir) refer to North Korea as simply "Korea".