1. Oxygen masks
More importantly, at high altitudes, people have 15-20 seconds before passing out. Put yours on first, then do your kids. Passing out for a few seconds won't harm the kids.
2. Water in lavatories
Check the outside of the aircraft when walking in. If the paint isn't in good condition, then the plane is most likely not in good condition as well. Skydrol (hydraulic fluid) is a nasty fluid and will dissolve everything. So if the paint is missing, it's most likely from a skydrol leak. No one wants a hydraulic leak at 35,000 ft in the air. As you can't just pull over and top the reservoir off.
3. The lights on the airplane dimming when landing
4. The Captain's authority
The captain has almost limitless authority when the doors are closed. He is allowed to arrest people, write fines and even take the will of a dying passenger.
5. Lavatories can be unlocked from the outside
6. Flying with pets
7. Never drink water on a plane that didn't come from a bottle
8. Lock your bags
9. Hard landings
"Landings are nothing more than controlled crashes", according to a pilot.