Duke: Technically, we don't exist. We answer to no one. And when all else fails, we don't.
In the underwater scene when Rex blows up the ice pack, ice appears to be denser than water in this situation. The ice sinks when it's blown up, and even if there were pieces of metal on top of the ice, it shouldn't. Some pieces the size of a five-story building have no metal and still sink.
G.I. Joe comics creator Larry Hama has a cameo as a general during the NATO briefing scene.