To prepare for his role as Firefly, Ray Stevenson read the G.I. Joe comics. He became a fan of his character, even putting in his own money so that the costume designers would make a mask to go with the costume.
The Project Zeus orbital weapon depicted in the movie is based on a real concept and it is theoretically possible. United States Air Forces's Project Thor, nicknamed Rods from God, it is based on the principle of Kinetic Bombardment: tungsten rods are dropped from a satellite in orbit and, depending on its size, could destroy from deep bunkers to whole cities.
The cliff battle scene took two months to film.
In the G.I. Joe saga, Zandar was Zartan's brother. Here, he is a Secret Service Agent of Zartan/President. He is listed in the credits as Havoc (which is the name of Cross Country's vehicle.)
Sienna Miller, Joseph Gordon-Levitt and Christopher Eccleston declined to reprise their roles from the first film.
Arnold Vosloo: His face is only seen for roughly three seconds (not counting the few times you see his photo on a computer). The rest of the time his character is played by Jonathan Pryce as Vosloo's Zartan is impersonating The President via the nanotechnological disguise.
Jon M. Chu: [Hip-Hop Music] Roadblock recites lyrics from "Don't Let Me Die" by Jay-Z while briefing with the remaining Joes.