Wyrrir

But that scene (when Gu-hyeon is gathering his papers on the road and almost got hit) was in NGNL too (near the end of ep5).

No Gain No Love, for example.

He said in the end of ep. 10 he believed her. Then, they talked about it more in ep. 11.

She returned to her body in the hospital days/weeks/month(?) later and her clothes didn't change.
As for the cut on her back, before she traveled to the past she had fallen to the mirror crashing it. I guess people on the plane simply thought pieces of the mirror injured her.

Flex X Cop
Military Prosecutor Doberman
Behind Your Touch
Study Group
The Trauma Code
The Kidnapping Day

It's not an important part, just a subplot with a few scenes.

Script.

She is 35 (that's not almost 40), he is 24 (25 within about two weeks).
She couldn't be his mom.

Yes, there is romance, but it's not incest.

No, far from it.

I don't know. Maybe I see it too darkly.
But Ryong already was in a serious condition, and he was warned he'll lose his eyesight and ability to walk even if he returns immediately - but he didn't plan it at all.
And Byeol... scientists didn't have a solution (or even a slight idea) how bring her down to Earth. And if they manage to do it...? She spent her entire existense in zero gravity. What would gravitation do to her (or the forces during the landing)?
So, when I watched that scene I thought, it wasn't real, only an imagined moment from Ryong (like Eve's fantasy about their life together).

Yeah, I didn't. It wasn't bittersweet for me either. Just I think that could be the intention and maybe someone who is lost enough in the story or attached to the characters feels that way IF...
(you don't think about how silly decisions were made; and that Ryong and his daughter are 'dead' too since they can't return to Earth and survive the process or what comes after it - and they can't live in the space for decades)

I think the body isn't dead. After all, it's not just some kind of muppet, moved by Gangcheul. The vital fuctions are still working (and they've worked all the time - execpt those few minutes before Gangcheul 'moved in'), his heart is beating, he gets tired and hungry, he can bleed etc.
Based on other kdramas where a body was taken by another soul that state won't be an obstacle before a relationship (even a physical one).

In the drama, age difference was around 7 years. As I remember, based on what they said about how much time had passed since particular events, and how old characters were at the time those events happened, ML could be 25 and FL 32 years old.

I think it was meant to be a happy ending (or happyish).
I can't see it that way, though. For me, it was rather bittersweet, not really satisfying.

Maybe he was studying in the USA for years, and during the attack just visited his family.
I think in that scene the other kids speak about two different events: Geon-yeop's departure in 7th grade (so most of them didn't even remember him) and the attack against him and his mother (which happened a year ago).
But I don't know. It's not quite clear (or I just don't remember every detail correctly).

Ga-min also looks much younger in the flashbacks one year before (when he is with his teacher or when he decides on studying in Yusung).

Yes.

No happy ending. (Bittersweet, at best. As long as you don't think too much about what will happen with the characters after that... or what decisions led to this situation.)

His character's love interest is Eve Kim (Gong Hyo Jin).

Yes, there is.