Brian and Stewie's bullet wounds in their feet disappear when "democracy kicks in".
Muddy Waters's guitar has only four tuners, not six.
When Stewie shoots the piano player and his friend there's a photo on the wall where the U.S. flag is attached to a pole on the opposite side of the blue field.
The drill sergeant's stripes are upside down.
The flag patches on the right shoulders of the Army Combat Uniforms consistently violate US Department of Defense regulations. The blue field should be at the front (right) but is shown at the back (left).
In the scene showing the school the night of the school dance, the school's sign has a spelling error. It clearly reads "JAMES WOODS REGLONAL HIGH SCHOOL."
When Chris stumbles across Mayor West playing poker with dogs, one of the dogs is holding an ace of hearts but the ace is black instead of red.
The army recruiter calling himself "Major Awesome" is wearing a four chevron rank insignia which does not exist in the US military. The actual insigia for the rank of major in the US Army is a gold oak leaf.
The recruiter confirms to Stewie that his pistol is a Beretta M9, but it is actually a Colt 1911A1.