When Maggie enters the suspect's house with her firearm drawn, her pistol has the end of the barrel exposed meaning that the slide is racked in the recoil position. In this mode, the gun is unable to fire and the slide normally locks in this position when the last round of the magazine has been fired. This is an oft-repeated mistake in many TV shows and movies. Semi-automatic pistols are often locked in this position to ensure safety in handling and storage.