I’ve been meaning to get around to reviewing this.
The Dominators coming to Earth because of a threat to their slave trade is your favorite idea, but this is the first time we’ve actually seen their point of view on it. That certainly made a poor impression on the buyers. I’m guessing their collaborators on Earth didn’t tell them about the Metahumans on a “what they don’t know won’t hurt them” idea. That didn’t work did it? .
Calvin Hobbes (great name choice by the way) certainly had a bad go of it didn’t he? An excellent example of how suddenly getting powers can’t totally ruin your life.
Definitely want to see this continued.
Actually Calvin, Mon-El was speaking Daxam. “By remarkable coincidence Daxam and English sound exactly the same”. Hey Supergirl, guess what? Your boyfriend is a slave owner on this Earth too.
An entire fleet is coming to Earth? That’s...not good.
Good start and definitely hope this is continued.

I loved this one-shot.
For Flash, the first episode was nearly unwatchable (as someone who studied physics, the technobabble was too unbearable, even compared to S3/4/5). The second felt a bit mediocre, but given your recommendation, I'll watch the third soon.
On Arrow, I say it's good if not perfect [flashforwards]. My only excuses for them is that Adrian was the Hood while Robert was the [Green?!] Arrow, and Black Siren had not heard of Thea's death in the midst of going to some meta-prison, being a part of Zoom's army, and going to E-1.

solid story and nice return to the fandom. as for the discrepancy about the Hood, TVLine touched on it the morning after the season premiere aired and it makes some sense. Here's what they said.

DIDN’T THE FLASH ALREADY ESTABLISH THAT ROBERT QUEEN WAS ‘THE HOOD’ ON EARTH-TWO?
Yes, an Earth-Two news broadcast in The Flash 206 mentioned that Oliver Queen did not survive The Queen’s Gambit‘s sinking, and thus Robert Queen went on to become The Hood. And yet Adrian Chase was revealed as The Hood in Arrow’s season opener. Guggenheim explained on Twitter that, Diggle included, “More than one person has worn the hood on Earth-1. Why assume things would be any different on Earth-2?” He added that the apparent passing of the Earth-Two baton “is a reflection that 6 years have passed” since Papa Queen turned vigilante.

As for Thea's fatal OD, it might've happened after Laurel left Starling City and she honestly didn't know about it, given that she was dealing with her new powers and working for Zolomon. Just my two cents. Also, loved the Calvin Hobbes bit

Welcome back to the act, my friend! And what a great way to return with this idea. Poor Mr. Hobbes but at least he's thankfully at peace now.

Two other continuity errors being a lack of a golden tint and an old school look to Earth-2.

I enjoy the refreshing take on why the Dominators invaded, and how you tied it in with the established characters of the Arrowverse including the characters specific to that crossover arc.

Most of all, however, as a fan of Waterson I appreciated the OC's character name, personality, powers, and implied history.