If a train is crowded enough, there can be a phenomenal amount of physical pressure exerted on standing passengers. On three different occasions, my feet have lost contact with the floor of a train due to the pressure of the shifting mass of bodies as we rounded a curve.
In Tokyo, there are often trains running on parallel tracks. At times, you can see clearly into the next train as it runs next to yours at the same speed, just a few meters away. You sometimes make eye contact or notice interesting things about the strangers in the other train as they look back at you. Nobody ever waves.
Sometimes I can’t quite make it to my desired car on the train before the doors close, so I get on and begin walking down the length of the train on the inside. If I’m walking opposite the direction the train is travelling, there is a brief moment when it begins moving that I am walking forward but the platform out the window seems stationary, giving the curious sensation that the floor is travelling beneath me, rather than me travelling across it.
From where I live in Saitama Prefecture, Mt Fuji is sometimes visible. You need clear weather, though, and you need an elevated position. Most of the time, if I can glimpse the mountain, it’s from the train as I commute into Tokyo. I consider a clear sighting as a good omen for the day.