After Crocket escapes, the helicopters that are searching for him are clearly marked "Army", not Marines. The Helicopter that the Marines rappel from is properly marked.
The emblem of the 1st Cavalry Division, of the U.S. Army is clearly visible on one of the "Marine" helicopters.
When Meg notices the Wimbledon Cup awards on the wall in the Gunny's room, Harm says that it is the Marine Corps Wimbledon Cup. It is not a Marine Corps competition. The National Rifle Association administers the Wimbledon Cup competitions each year.
When Meg is preparing to join the Marine company to search for Harm and Gunny Crockett, Col. Gordon says "I hope that the JAG officer knows how to cover her back". His mouth is very obviously saying "cover her ass".
Colonel Gordon's collar rank insignia is sideways, the wings of his eagles should be pointed up towards his collar bone, not the head of the eagle. This is a uniform mistake no Marine Corps officer would make, let alone a full bird Colonel.