It was no secret that the trains in Gotham were damaged, whether it was from all the explosions that flooded the city on a daily basis or the fact that the rails were broken wasn't completely clear. At that point, what was once a train station was nothing more than an empty place used by some homeless people to sleep.
Or that's what it was supposed to be, because while the station was damaged and underneath the city, it was actually active. It just had another kind of train, a slightly more interesting one.
In Danny's defense, he was extremely bored and there was an abandoned train station he could use to play with. All it took was calling in a favor from Technus and a fully functional ghost train connected the Infinite Realms to Gotham.
The ghosts, of course, used this for fun. Fighting each other, chasing each other, celebrating, having concerts. It was a way to go to the human world without anyone causing trouble for them, not that anyone was paying attention anyway.
Or at least, no one was supposed to be paying attention, because Waylon was dumbfounded at the sight. He had escaped to the old rails when he had no other choice, his sewers were compromised and he needed a way out. He didn't expect to walk right into a party, or be offered a sandwich with a smile instead of a shout.
He could also observe a clearly glowing train and the fact that everyone there was glowing. They could be metas, or another completely new creature, but Waylon didn't care, they gave him food and he wasn't a snitch.