Series Finale was good and all, but totally messed up their timeline...SPOILERS
From the episodes 19-21, "Is This Henry Mills?" "Homecoming" and "Leaving Storybrooke" is an ongoing story, though I guess if you want to skip "Is This Henry Mills?" that's up to you, but it all ties in well together, wrapped like a nice present for fans.
In "Is This Henry Mills?" we learn that teenage Henry is about to graduate and adult Henry is in the past with his family, Regina, Wish Hook, Robin and Zelena....and others < but that's not what's important.
At the end of "Homecoming" Robin and Alice head to Storybrooke as they need to "get some friends"
So, I'm thinking at this moment, Henry has already went to new realms (I don't exactly remember what they called it) -But my point is it would've made sense and solve the problem I saw in the finale. Also, Regina, Zelena, and Robin should've already been there too and no longer be in Storybrooke. Though, Robin did "grow up" in Storybrooke, so...that's another problem. But anyone could've forgot about that Robin backstory...I did. I'm following our main characters stories to the last thread, not our recurring characters much.
In "Leaving Storybrooke" Robin and Alice arrive in Storybrooke and we see a Zelena with a little Robin!!! What on earth were they thinking? "Current" Zelena would remember this ..."mission"
I don't know why "Kelly" wouldn't go along instead of this and come up with the idea to go to Storybrooke and getting Snow and David. If things aren't more complicated Zelena says Regina and Emma aren't there because they took Henry on a college trip...again Henry and Regina should be no longer there. And in "Is this Henry Mills?" teenage Henry found the bean, he should've left the next day, not going on some college trip. This kid craves adventure why would he waste more time...if talking to his future self wasn't enough (yeah I know, he didn't know about that, but we did). As for Emma, they've could've said she and Hook are on a trip.
This "Wish Realm" gives us a young version of Henry, who teams up with over the the top evil Rumple to change everyone's stories and be alone. Pretty evil. But the fact that it gives us double vision leads to more confusion.
After Rumple saves Wish Hook and reunited with Belle in the afterlife, Regina has a big plan of connecting/merging all of the realms together, so no one will be separated again. So...if "original" Henry, Regina, Zelena, and Robin never went to the new realm world.....what?? So, now there should be an extra pair of Henry, Regina, Zelena, and Robin.
I guess it's not really "that" big of deal, but it's still annoying to viewers like me that point out every little detail. Since Once has a bunch of worlds within worlds, these "plot holes" can solve themselves.
It says "several years" later, well Lucy didn't age, so I'm guessing it's a a few months later when Regina is crowned Good Queen of new "world"
Edward Kitsis and Adam Horowitz can pull any explanation they want out of their "hats" but in the end, they can do what they want and they did. They just wanted that "happy ending" for everyone...