Wow without the mask on the Enemy Guard Uniform still does add to Raiden's "camo index". I heard it on the UKnighted stream and thought they were full of shit but it's completely true. Guards have to be a little bit closer to notice you.
Another cool detail I never noticed before is that when you meet Olga on the heliport, you will start with your M9 after the cutscene finishes if that is what you have equipped, otherwise if you go in with your socom or unequipped you will start with your socom after the cutscene finishes. You see similar stuff elsewhere, like having the M9 before meeting Vamp for the first time as opposed to not. Changes the cutscene a little bit.
ANOTHER detail I noticed is that on Scott Dolph's terminal, Snake or Otacon try to login as root and fail. Then they log on as user scott and the password is the same number of asterisks as Helena.
So many details in this game...everything is details...I can't....