You never know what will happen in future when you get into grave danger as the accidents will happen. If you are prepared for the accidents then probably there are fewer chances of survival.
There are extra batteries which you can carry in each trip. If you want to use AAA size in the slot then you can use Aluminium foil. You can place the battery and fill the upside or downside gap then it is a conductor of electricity which will flow the energy.
2. Cigarette knife
If the filter is used as a knife then it can be dangerous. You can fire through one end part of the filter and a knife is ready.
3. Pure water
If you ever found don't found in fresh or pure water. You can use a cloth to remove the dirt and harmful bacteria.
If you ever found yourself in locked car then you can use any sharp object to break the window. You can use sharp object to punch the window.