bus

After one hour I realised that I was in the wrong bus.
After one hour I realised that I was on the wrong bus.

I fell when I was getting out of the bus.
I fell when I was getting off the bus.

We say in the car, but on the bus, on the train, on a ship and on a plane.

We say get in/out of a car, but get on/off a bus, train, ship or plane.