Borderlands 2 - Where Angels Fear to Tread

During the mission "Where Angels Fear to Tread", you are tasked with infiltrating a Hyperion compound. At one point, you come to a large locked gate and are instructed to destroy the two turrets on the outside which will "maybe get them to open the gate". Since this doesn't seem to make any sense, it is likely a reference to the classic Konami game Contra. During the opening level of that game, you traverse a similarly rocky terrain with patches of grass, fight men in suits with power weapons, fight off flying attackers, cross bridges and at the end of the section, you must destroy an automated turret above the gate to enter the building.