That are perfectly normal for you, but that others wouldn't be aware of.
For example,
I used to work as Cabin Crew for a long haul airline, here are some thing I know from doing that job.
On a plane, there is a small vent on the bottom of each toilet door. This is there to regulate the air pressure inside the cubicle when you flush, without it, the toilet doors would literally be sucked off their hinges and bad things would happen.
When you see planes parked up around the airport with covers over the engines and orange ribbons hangings off them, the pilots refer to this as the plane being "cold and dark". When I first heard this I thought they were just being sentimental and "worried" about their precious planes, like how people sometimes name their cars. Nope! It just means there is no power to the aircraft so the lights and heaters don't work, the plane is literally cold and dark inside.
Cabin crew don't get paid until the doors are locked. So be nice to them at the gate or when you're trying to find your seat. At that point they are literally working for free.
Your oxygen masks don't inflate and are getting their supply from a chemical filled container just above your seat. The reaction between the chemicals releases oxygen for about 15 minutes. There isn't some big oxygen cylinder full of fresh air. It's just a small cannister about the size of a coke can. That's why you MUST put yours on first, before you try to help anyone else.