The M11 in-game is modelled after a semi-auto civilian variant of the MAC-11. The closed bolt of the weapon is the telltale sign.
There is a strange animation that plays when attaching a suppressor to the weapon. The suppressor is not actually screwed to the barrel's threading and is rather put a small distance before it. When the player takes off the suppressor, the suppressor is seen being threaded correctly off the barrel, even though it was never there in the first place.
If a player aims down the sights of the M11, the sights are actually misaligned. The rear sight is too far down, and in reality, this would mean that shot placement would be higher than where you aimed.