1. The structure of this episode is incredible. It pulls you in with the soap opery goodness and then just gut punches you at the end with complete no holds barred destruction. And it's completely out nowhere. It gets your guard down (you're more concerned with the Rogue/Gambit/Magneto dynamic and the Genosha intrigue and then BAM. Loved it.
2. Beau Demayo, who was the showrunner and lead writer before getting fired* right before the series premiered, said that he wanted this season to start off nostalgic and familiar and then shatter that. This episode succeeded in that. He said his inspiration were things like the Tulsa Massacre or 9/11, where you have a sense of peace and prosperity that is then shattered by the hard reality of ultraviolence and hate. He did that really well here. We go from Genosha as a near mutant utopia to being obliterated.
3. Loved all the mutant cameos on Genosha. Glad Nightcrawler didn't die. Gambit was a gut punch and I think they may really keep him dead. I'm assuming Magneto survived somehow (I'm guessing Leech used his powers to dampen Magneto's getting the Sentinel to back off due to not reading him as an Omega Level Mutant).
4. The animation in this episode was slick. A lot of those motorcycle scenes reminded me of Akira.
*We still don't actually know why he was fired. Rumors are he's a toxic guy to work for and treats his staff pretty badly. It also probably doesn't help that he has an Only Fans page and likes showing his wiener to the masses. Regardless, he's clearly got a gift for writing X-Men, and he was able to finish Season 2 before he got canned, so that's good.