When Katniss received her new, awesome bow from Beetee, she was admiring its features when she said that there was an option of "voice override" for the arrows but that she would probably never use it. Does the voice override mean something like turn off their features, essentially reverting to normal arrows? Or was she actually referring to the bow? Would they be overridden with "Good night?"
What little evidence there is in the books:
The arrows that Beetee designed are no less remarkable than the bow. Between the two, I can shoot with accuracy over one hundred yards. The variety of arrows--razor sharp, incendiary, explosive--turn the bow into a multipurpose weapon. Each one is recognizable by a distinctive colored shaft. I have the option of voice override at any time, but have no idea why I would use it. To deactivate the bow's special properties, I need only tell it "Good night." Then it goes to sleep until the sound of my voice wakes it again.
-The Hunger Games - Part Three: Mockingjay, Chapter 5.
All that Katniss knows about the voice-control part of the bow is:
- That it wakes from sleep when it hears her voice
- De-activates when she tells it 'good-night'
We have to remember that the entire story is narrated from Katniss' POV, so if she doesn't know any further details, then we don't know either. This is further confirmed in the wiki entry.
Is it the Arrows?
It does seem like she is talking about the arrows in the passage, so it is possible that the 'voice override' part is referring to toggling through the different types of arrows:
- Razor sharp
Since she needs to be aware that the arrows are stored in separate parts of her sheath:
Finally, he [Beetee] straps a sheath divided into three cylinders of arrows to my back. "Just remember: Right side, fire. Left side, explosive. Center, regular. ..."
-The Hunger Games - Part Three: Mockingjay, Chapter 6.
So the 'voice-override' could allow her to just grab any old arrow, and tell it what type to be (Fire, Explosive or normal) to save her from making a mistake and grabbing the wrong one, perhaps.
Is it the Bow?
The only part which bugs me is where she says
but have no idea why I would use it
This tells me that it (the bow) has a little bit more to it; my assumption is that since Beetee is essentially a techno-genius, it would not be [too] difficult for him to program some AI into the bow. He could have programmed some auto-aim or some similar feature into the bow to improve Katniss' survival in a war. But Katniss believes herself to be so adept at using a bow that she immediately dismisses her need for any of these 'special properties'.
Either way, it is an incredible bow which has properties that we don't know of, since Katniss doesn't tell us, or use them at all.