Not only that, but the last two also have incorrect rifles.
The guy in the woodland BDUs is the one who should have the M16A2 that the Vietnam grunt has. The guy in the desert BDUs should have an M4 (or M4gery). While the Army is now purchasing M16A4s (20" flat tops with the Knight's RAC foreend) the M4 is far more common in front line Army units.