Technology-wise, the series has always had it's issues. For example, MGS takes place in 2005. The weapons and kit used is very old for that time...I mean take a look at what soldiers in the GWOT were using at that point and compare it to the "Space SEALs" and so on. FAMAS rifles for a US SOF unit...yeah, right. In reality, they'd be running HK416 assault rifles with all the latest and greatest gadgets.
Obviously, being that the game came out in 1998 and was in development prior to that, it's understandable to a degree (even at that time, they'd be running an M4A1)..but just something I've thought of before.
Another thing I've noticed, look at the simplistic design of Snake's suit in MGS. Compare that to the older designs from Peace Walker, GZ, etc. You basically have an evolution from the MGS3 prototype suit, to MPO to PW, then to the flightsuit like sneaking suit of MGS, to the Octocamo. Seems that something like the Octocamo, or at least a prototype form of that suit, would've been used in MGS. If that makes sense.