The film was shot and completed in 2009, and originally scheduled for release on November 24, 2010. It was shelved for almost two years, due to MGM's financial troubles.
The invading army was originally Chinese. It was changed to North Korean in post-production to maintain access to China's box office.
Changing the antagonists from Chinese to North Korean reportedly cost less than $1 million. They changed an opening sequence summarizing the backstory (Chinese "repossession" after the U.S. defaults on loans turned into a North Korean invasion), re-edited two scenes, and used digital technology to change Chinese symbols and dialogue to Korean.
When the group is talking about things they miss, one person says Call of Duty 4: Modern Warfare (2007). One stage of Call of Duty: Modern Warfare 2 (2009) is called "Wolverines", taken from the original movie, in which Russia invades America.