Arrow: 7 Plot Threads The Show Totally Abandoned
The final season didn't wrap everything up...
Arrow's series finale was an episode that spent much time reflecting on the past. In fact, you could even say that's pretty much what the whole final season was about - y'know other than serving as a teaser to Crisis On Infinite Earths - as the series drew to a close by celebrating its greatest hits, fixing some of its worst mistakes and tying up a lot of loose ends.
Yes, Season 8 was very much a farewell tour for the show that started it all for the Arrowverse, with an abundance of references to days gone by, nods to some legendary DC Comics characters that it never got the chance to adapt and even a few hints of what's to come in the future (Green Arrow and The Canaries).
That being said, the final season was also the show's last chance to address some of its longest-running mysteries and give them the closure that they needed. Unfortunately, with the series finale - and, by extension, the whole series - in the rear view mirror now, it's safe to say that it wasn't effective in tying up everything...
7. Deathstroke's Search For His Other Son
Slade Wilson's return in Arrow's Season 5 finale brought with it a highly-compelling two-parter in which Oliver's former enemy attempted to track down his son Joe Wilson. Upon doing so, he learned that his beloved son had become a mercenary - but as upsetting as that was for him, it wasn't the biggest shock he received that day, as he also learned that he had another son: Grant Wilson.
While we had met an alternate version of Grant on DC's Legends of Tomorrow, the reference to him here suggested that he was going to make his debut in the main timeline of Earth-1 - but not before Slade went off to track him down.
However, Grant did debut in Season 8 - with Jamie Andrew Cutler reprising his role - as the leader of a preliminary version of the Deathstroke Gang. As this was little more than a plot device to force the time-traveling Team Arrow kids to be honest to their fathers, there was no time spent on giving Grant a backstory. Naturally, we're all left wondering if Slade ever found him in the two years prior...
As Crisis On Infinite Earths more than likely undid all of that, we may never know...