I was joking they'd just kill Alex off in the last episode off-screen with clever editing and looped dialogue, but I didn't think they'd actually do it (my friend who's been watching the show with me had his money on Alex deciding to have extreme plastic surgery between seasons to represent the finality of his divorce and estrangement from his family; "new face, new me"). I imagine that the technical aspect was a bit involved. There were only a couple of scenes that mentioned his death directly, all on the Rocinante and only involving a two or three characters at a time, so I assume those were reshoots done as the very first thing when filming started on season 6. Anvar was probably painted out of shots he was in during the party scene (there were a couple of conspicuous gaps in the staging, and Avasarala was obviously looped when she mentioned it to Bobbie).
We'll probably never see it, and I'm sure just reading the book would give us a decent idea, but I'm curious about what the rough-cut of the episode as originally shot looked like with Alex in it.
As for the manner, I respect it. They talk all the time about how dangerous high-g flight is, they probably were due to pay it off with a random death (and I understand in the corresponding novel, a different character did have a stroke and die because they were going too fast for too long), though in a perfect world, it would've been nice if it was a bit less abrupt, if there'd been any subtle sign Alex was woozy or otherwise at death's door. On the other hand, I'm not sure it wasn't realistic for that sort of injury to be fatal without the victim having the faintest idea anything was wrong until the moment they die.
Putting aside that elephant in the room, I died laughing at Amos's extremely Amos attempt to tactfully talk Holden in to letting Clarissa join the crew, leaving him too confused to even understand what he was agreeing to.
Naomi jumping out of the ship not to be rescued, but as a last-ditch attempt to keep her friends from getting themselves killed by Marco's trap was just perfect, as was her and Holden listening to her last message together.
I was on my feet cheering when Drummer decided she was through with Marco's bullshit and saved the Roci. I do agree that the full dynamic of her and her crew/family wasn't really explored enough for it to land. I mean, I get that Marco killing his hostage in response was a blow, but they mostly seemed somewhere between mindlessly sanguine and hopelessly naïve Marco systematically killing everyone Drummer had ever cared about wouldn't have gotten around to them, too, even if she had been his perfect little pet. I was waiting for someone to point that out, to ask if they would've killed Drummer when Marco asked them to do it, or they would've wanted Drummer to kill them on Marco's order to keep the others safe.
But, what the hell happened at the end? I'm still confused. It is clear that there is some fuckery going on in the Mars establishment, they're in league with Marco, which has been pretty clear, but what was that colonised planet? The ship in orbit looked way too big to be any ship we know of? And what exactly happened at the end?
I haven't read the books, this is all just based on what I've taken from the show.
Admiral Sauveterre has apparently set up his own splinter faction of the Martian military (possibly most of the remaining Martian military). He was supporting Marco's terrorist actions largely as a feint. Someone aligned with Sauveterre identified a planet which had intact ships from the civilization that built the Rings and protomolecule in orbit. Sauveterre wanted those ships, specifically, and advanced protomolecule-builder technology in general, so he could build better version of the pseudo-fascist ideal of Mars. What he needed from Marco was to get the last live protomolecule, which Fred Johnson had, and the last live protomolecule expert, which Anderson Dawes had (the scientist, Cortázar, from season two. We heard Marco kidnapped him earlier, and a message from him popped up on Sauveterre's screen in this episode). Marco causing chaos throughout the system was a general bonus, and being able to co-opt Medina Station and control of the Ring-Space from the inside meant Sauveterre could just walk to his alien fleet rather than fighting his way to it and defending it once he got there, but I'm sure Sauveterre only really
needed the protomolecule materials to give him the spark and the know-how to reactivate the alien technology.
Now we have a cadre of fascist (formerly) Martian fanatics with a cache of unbelievably advanced military technology and the means to potentially exploit it, as well as total military control of the Ring Space, potentially putting a stop to all emigration from Earth, Mars, and the Belt to the other habitable systems (I'm not entirely sure what Sauveterre meant when he said he'd mined "his side" of the Ring, if he meant his side of the Sol Ring, or the Ring to his new system). Which is bad, since Earth is now in powerful need of being evacuated.
As for the closing shot, the entities that destroyed the aliens that built the Rings have seemed to be reawakening since humans started using the Ring gates. Holden saw ghosts of them whenever he transited, but what happened at the end of this episode was certainly more than that. I'm not sure what to make of it, if it was entirely figurative, showing they're awake and active again and soon to be on the move, or if they attacked Sauveterre's ship as it transited the ring, or somehow attached themselves to it (or the crew), but it's definitely a striking image to end the season on, and I'm sure we'll find out exactly what it meant in a year.
ETA: Okay, I read the post just above this, so now I know. But, still. Striking.