One thing that irked me about ID4 (after I went into the AF) was the gate guards at the desert base. I'm guessing that was Area 51.
Since when the hell did gate guards start toting MP5's? An MP5 is a CQB weapon, not for shooting over open areas. The weapon of choice would be an M16 or an M4, depending on the armory of the unit.
Also, the SP's at the gate would have head gear and would not be wearing black. Nothing says shoot me like wearing black in a brown desert.
Another thing, no SP in his right mind is going to allow a fleet of cars and trucks into a controlled are (Area 51) without authorization, especially into a sensitive area, no matter what the cargo may be.
Just my .02 being a former SP.
Inaccuracy is one thing that drives me nuts about military movies. I try to avoid thinking about it now because "it's only a movie."