Originally scheduled to be released on November 24, 2010, the film was shelved due to MGM's financial troubles. While in post-production, the invading army was changed from Chinese to North Korean in order to maintain access to China's box office.
The invading army in the original 1984 movie was the Soviet Union, which no longer exists, and Cuba. The Democratic People's Republic of Korea (North Korea) was chosen as the enemy in this updated version.
When the group is talking about things they miss, one of them says Call of Duty Modern Warfare. In Modern Warfare 2 there is a stage called Wolverines which was taken from the original movie, in which a foreign Army is invading America.