In the beginning of the Bootcamp campaign, you're running around in the VR world and your CO spawns a Slammer that used to fire its main cannon. Now it doesn't fire anymore but you still complain about the noise!

At the end of the Bootcamp campaign you see two Kajman gunships flying away from the city and a jet fighter in the distance. The jet fighter used to chase the Kajmans away but no more, now it just looks random.