As usual, world A is the one where ML's father dies, and world B is the one where he survives and the later killings happen (blue tint).
Other posts about plot issues:
https://mydramalist.com/52351-train#comment-6717695 : I will point at but not steal the important note that the many years between the first murder and subsequent ones are not that believable
Other posts about the internal rules:
https://mydramalist.com/52351-train#comment-10106459
https://mydramalist.com/52351-train#comment-10106503
- FL's disabled step-brother attacks them for no reason in the first episode, even tries to kill at least FL, but is allegedly afraid of dead bodies and death himself.
- in E7, ML-B is permitted to visit FL's disabled step-brother, even though ML-A was refused the same thing categorically. since ML-A even assaulted him recently, there's no way this would fly. ML-B even assaults him again first thing!
- first time it's a real train E1, second time it's a ghost train E2? or how? at the end of the show, ML seems to be trying to get run over by a train, and yet uses it to reach a new world. just what.
- if train just zooms through, how can the raincoated figure get on or off? are we supposed to believe that the train stops when there's rain, and doesn't stop when there's no rain? (in E01 we see the raincoated figure get off rather than just throw a body out)
- in E7, how does ML-B get on the train back to world B when the train does not run anymore?
- in E7, how does ML-B get on the driving train, anyway?
- what's up with the time 21:35? why is it the "train time"? 21:35 is the moment of death for FL's father, but otherwise has no significance.
- why does FL's father's watch stop at that precise time? he isn't thrown to the floor very forcefully, just a mild thump, and the hammerer doesn't hammer the watch.
- the sequence where ML-A and FL-B whisper to each other and see each other on the railways despite being in different worlds is just nonsense
- the killer's mother is magically the detective in charge of the murder committed by her son, and the son even knows this in advance and leaves evidence specifically for her to know it was him.
- the timeline in 2008 is somewhat inverted nonsense: FL and the detective arrive at the hospital before ML's father is brought in by the ambulance, even though it takes time for the police to reach FL's home, to check the scene and interview FL, and to drive her to the hospital, while the father has to run out and be hit by the car (or not) in advance of her even getting home. also, how far away from the home can this be for the attempt on his life to be plannable? they can't know what way he runs, so they can't wait far away, but when she gets home, there is no crowd and no injured body anywhere. the only real flexible time window is how long ML's father is knocked out inside the home next to the dead body, but that isn't particularly relevant.
- it's not explained in any way:
—why the two chose the stepfather's house to rob
—why the two took the jewelry and chose that particular M.O., and what relevance FL's mother's jewelry can possible have for the killer
—what kind of communication the raincoated figure from world B has with the body-hiding helpers (FL's disabled step-brother and his mother) in world A.
—why throughout the show the police has CSI-level hyper-detailed photography of each piece of the stolen jewelry as if it was for auction at Sotheby's rather than a mother's personal jewelry stash
—how the world-traveler has so many worlds to go between; I suppose it's left open as obviously the explanation would be too ludicrous (different trains, different times, different stations? is there a map?)
—when the "fates split" between worlds A and B: initially it is said to have happened at the traffic light / crossing some minutes before the killing, but then it is revealed the umbrella moment still happened in world B too. so it's a different moment earlier or later that the show doesn't really elaborate on.
—how some different choices in a recent timeline junction can possibly change the entire architecture of a city
