The shimmering surface of the mirror gives way as you pass through it. You feel a stinging cold for just a moment, then find yourself standing at the front of a long, narrow train car.
This new cart is painted in calming pastels, and a variety of children's toys lie abandoned on the seats. You can almost feel their gaze as you pass them by, silent and forlorn. As you get closer to the end of the cabin, you start seeing potted flowers on the seats, placed upright as though they were passengers. Most of them have wilted, but a few are still in bloom, white petals unfurling hopefully towards the dim fluorescent lighting.
Once again, there's no door when you reach the end of the cart. There's nothing there at all, in fact; the wall is missing entirely, and all you see in its place is a deep, dark void. You feel a light, gentle breeze flowing into the cabin, and as you get closer you can hear a soft humming sound. You cautiously reach out a hand. It disappears immediately, swallowed by the darkness, but when you pull it back it emerges unharmed. You glance back at the cabin. The smart thing to do, you know, would be to turn around and make your way back to the first car. The fun thing to do, though, would be to see what's on the other side. After all, you've survived everything else the train has thrown at you, right? A little stroll between dimensions never hurt anyone, probably.
You turn back to the thrumming abyss, take a moment to steel yourself, and calmly walk forward.

You blink. It takes you a moment to orient yourself in the blinding sunlight, but after a moment you recognize your surroundings. You're at a train station - your train station, just a stone's throw away from your home. It's midday, and a stream of people pass by on either side of you as you stand unmoving by the platform. For the first time, the dull buzz of a moving crowd gives you a sense of familiarity and comfort, and your mind turns to your soft, warm bed. You put aside your fading daydream of a mysterious phantom train and join the throng of people heading towards the exit, eager to get home.
It's only after a moment that you realize you're gripping something tightly in your hand. It's a note, written on a crumpled piece of paper in an unsteady hand.
Thank you for riding with us, it reads. Please come again.