The commander states that "Greene took the LAPD's whole haul - that's over 700 rounds." That many rounds would fit in a single 6"x7"x12" ammo can that could be carried with one hand, but the load is described as being in multiple crates. In addition, the quantity is repeatedly described as a massive amount even though it's not even enough to give 8 men three magazines each.
The motorcycle gang are supposedly carrying rifles modified to use the tungsten-tipped ammunition. Penetrator ammunition can be used in any rifle of the correct caliber without any modifications needed to the rifle.
At the end, when Street leaves the SWAT yard on his motorbike, the gate closes down behind him. But it was already up, leaving the yard insecure, long before he went near it. It should have been closed, and only raised (presumably automatically) when he approached it.