The battlefield cross shown used an army rifle. Rifles are not kept by officers in their off-base quarters, they are stored on base at an armory.
The theft of the LAPD vehicle had two significant errors. First, officers would not leave a patrol vehicle running and unattended as was shown, and second the LAPD uses software that allows dispatch to see where every patrol vehicle is located. As such, the stolen vehicle would have been located within minutes of it being stolen.