Mei Ling, when introduced as a Navy Captain, is wearing a uniform called (Navy) Winter Blues. This particular uniform was phased out by 31 December 2010. If the game takes place in 2014, the wear of this uniform is improper, especially by a senior officer.
In this game, we're told that Para-Medic, the female doctor from Metal Gear Solid 3: Snake Eater, was Dr. Clark, who Naomi mentioned several times in Metal Gear Solid. However, Naomi always referred to this person as male. This is an unfortunate translational error: the Japanese language provides many gender-neutral terms, so Clark's gender was never specified in the Japanese version of the first game. The "Metal Gear Solid Database" which Konami have released fudges this by claiming Dr. Clark was secretive, and Naomi mistakenly assumed she was male as a result.