The name Callister — it's sci-fi and cool, and a lot of people may pronounce it Cull-IS-tah (rather than CALL-ist-er, in the show). But maybe it comes from the main character in Home Alone, Kevin McCallister, a really sadistic literal child. That story also takes place at Christmas in-name-only.
Aside from the sexualization of the women, none of the clones in Daly's game look much different from their real selves. The exception to this is Valdack, whose downgraded appearance in the game could indicate that Daly feels threatened by his more conventionally attractive coworker.
At first glance Daly turning Elena into a Blue-Skinned Space Babe makes no particular sense beyond keeping with the campy aesthetics of the Not!Star Trek. However, her digital clone skintone matches the colour of the nail polish used by the real Elena. Daly simply over-focuses on some minor details of real people he puts into his simulation.
Space Fleet is a pretty clear Expy to the original Star Trek, and presumably Daly is putting himself in the place of an actual character who is an expy of Captain Kirk. But if we consider it closer, while Captain Kirk is the cocky, admired, heroic alpha-male Daly clearly wishes he could be in real life, he is also respectful and caring towards his subordinates, forms a close team with his second-in-command and the ship's doctor to the point that they're an iconic example of the Freudian Trio, is aware of and takes seriously The Chains of Commanding, and clearly values cooperation and teamwork rather than solely making himself the Gary Stu hero who fixes everything — none of which applies to Daly. Assuming the Expy Kirk is anyway similar to the actual Kirk, and given the episode's overall satire of toxic fandom, Daly is almost certainly Dramatically Missing the Point of his favorite show by focussing on the surface-level heroics and ignoring the deeper underlying values.
The crew of the USS Callister getting new uniforms that resemble more modern uniforms could be a sign of how their adventures are moving past the campy antics of the original mod, or even possibly them being rebooted, mirroring the reboot films establishing that they took place in a universe that overwrote the original's via a space phenomenon.
All of the roles that Daly forces onto the digital clones are perversions of how they typically act towards him in their day to day life:
Nanette is an eager, intelligent newbie whose full of determination and clearly has a lot to say, and despite Daly's crush on her, he forces clone-Nanette to be a stereotypically demure, klutzy Damsel in Distress.
Walton's is quite obvious; he is Daly's ultra-confident and charismatic co-founder who can push him around occasionally, but is a cowardly wimp who defers to him on the fleet.
Lowry is an outspoken, confident woman who swears like a sailor, yet Daly forces her to be a Yes-Man who faints in his arms, and intentionally keeps the world sexless and squeaky-clean in terms of adult activity.
Elena is an Ambiguously Gay immigrant woman who is notably cold and distant to her coworkers, but is forced to swoon over Daly at his command and is clearly designed to have blue skin for the purpose of Daly's g-rated titilation at her "exoticness".
Packer and Dudani are Daly's underlings who don't really take him too seriously despite being perfectly friendly otherwise, and as a result, both of them serve the roles of "running" the ship and always defer to his word, despite that they are supposed to be computer experts.
The episode is unusual for Black MirrorEarn Your Happy Ending. Until you remember that the real Cole broke into Daly's house right before he died. Nevermind how she's gonna feel when she finds out, she left obvious thumbprints and presumably ordered a pizza to his house from her own phone. She's gonna be in a world of trouble when police start investigating the scene.
But given the appearance of the lollipop and the DNA scanner in the Black Museum and the fact that her digital counterpart is now online and capable of communicating, it's implied that the truth about Daly's activities and his death did come out, and that an investigation was conducted and his actions created a legal precedent making the use of DNA samples to create digital copies of real people to abuse a crime.
When Daly chokes Walton over the digital clones not having a found a signal yet, it gets even worse once you realize the science equipment on the ship doesn't actually work, as shown by that scene where Lowry tells Nanette to just press any button. It just does narratively significant things, and the narrative only happens when Daly's there, meaning there was literally no way for the crew to find that signal without him! He has it set up so he has a "reason" to torture them whenever he wants, and they have no way of knowing whether he's going to be in a bad enough mood to take advantage of it.
I see it more as him trying to look cool in his own story. Not just to torture Walton but to feel good about himself
The crew of the Callister didn't actually need the real Nanette to steal back all their DNA from Daly's apartment, though they may have thought they did; her actions being included is, in some ways, just for the purpose of having the audience consider how (even though saving the day) she is likely to feel horribly guilty or actually possibly get in real trouble about Daly's death. The inclusion of the lollipop in Black Museum could also potentially be because the police and everyone was so confused and horrified at a supposedly-stalker-level-admiring woman taking a lollipop from her boss before inducing brain death or locked-in syndrome enough to give him a slow, potentially-conscious, death.
Keep in mind that the police would probably investigate the purpose of the machine and not only would it not end up in a Museum of tecnological crimes,but they wouldn't put the machine next to it
In the first episode "USS Callister" the digital Nanette tells the real one to contact the Cyber crime unit and it seems a little strange that they'd be able to do anything about the situation — until you watch the rest of the series, and determine from the last episode "Black Museum" that there has been a history of digital cloning crimes and the Cyber police are probably more than aware at the time of "USS Callister" about the rights of detached consciousnesses so would have been able to put a stop to Daly's most-certainly-an-actual-crime.
Daly mentions that "no one dies in Space Fleet" unless he wants them to. Toward the end of the episode Walton performs a Heroic Sacrifice that causes him to be burned to a crisp by the ship's jets. It's possible that he didn't die from this as Daly didn't cause this and that he's stuck, burning eternally. The one remaining hope is that Walton was deleted along with Daly's universe.
I think thats what the fuck you at the end was for, so Daly would subconsciously hate him and he would die
Also occurs again when Daly breaks Walton by bringing Walton's son, Tommy, into the game, only to jettison him out of the airlock and making Walton watch his torture. It's possible as well that Tommy didn't die from this either, but now faces the eternal pain of decompression.
Unless he catches a lucky break, Daly is likely to die. The episode ends on the start of a ten-day holiday break, and with nobody to notice his absence since he spends his time in the game, it would be a few days after that he would be listed as a missing person. He would die of dehydration by the time anybody investigates his residence. Especially since he made sure to set his apartment door to "Do Not Disturb."
The digital clones, if they end up leaving the game and then are brought back by the DNA scanner, logically cannot remember what happened to them in the game previously. Maybe they've escaped before, and each time Daly has brought them back and punished them harshly for running away without them even knowing they could have done something wrong.
As much as Daly deserved his fate, what will happen to his company when it is found out that he seemingly died while playing a version of the game he helped create?
Presumably real-world!Walton would find some way to spin it to minimise the risk to Infinity's reputation, especially if real-world!Nanette came forward about the equipment and DNA samples she found in Daly's apartment. Daly seemed to be very much in the background of the company anyway (if Lowry is anything to go by, most employees saw him as a boss in name only) and what he did was heavily reserved for the technical side of things while Walton was clearly pretty much the "face" of both Callister and Infinity and was used to dealing with the PR side of things. It's not inconceivable that a story would be put out saying that "while the company is shocked and saddened by the unfortunate demise of Robert Daly, it's become clear that he was a potentially disturbed individual who lived as a recluse and therefore had no one to pull him from the game when it malfunctioned. This situation was a complete anomaly as our regular players can attest". Real life companies have survived much worse; as long as Walton knew how to spin it, the company would probably survive.
The choice of song is much darker in retrospect. "For he is a jolly good fellow... which nobody can deny."
Near the end of the episode, The game deletes Daly's mod while he's still inside, inducing brain-death in Daly. This is because the system is designed to recognize unauthorized mods and delete them. It's likely that (one of) the consoles for Infinity will be/is a PC, a system known for its modding community. Best case scenario, the dev team catches the critical error in time to fix it and prevent a bunch of deaths (unlikely, since they all went home for 10 days at least). Worst case scenario...how many people are going to die due to playing a modded version the system doesn't allow?
Since the regular game is an mmo, modding it is probably not possible for anyone but Daly.
Also, even if modding is possible for all players, Daly has developer access; other accounts would probably be locked out of playing while the game is updating, with Daly leaving a back door in order to fix any problems with the update procedure, to ensure everyone else's update goes smoothly.
Also real-life Dudani mentioned expanding the update (hence why it took until Christmas Eve to finish) and Daly zoned out because he was looking at Cole. It's possible Dudani's further updates removed all mods, something which would've been communicated to players, and Daly just didn't know because he wasn't listening.
The crew had the real Nanette steal back their DNA from Daly, but what exactly would keep him from just taking another sample and starting over? Yeah, it would have been more work than just resetting, but still, they lucked out when Daly got himself mindwiped.
The point is that even if Daly did ever re-upload their DNA, it would result in an entirely new set of digital clones who had never experienced Daly's mod before - and presumably the cycle could potentially repeat itself ad nauseam. Like if Daly ever re-uploaded Tommy, that digital clone would have no previous knowledge of Daly throwing him out of an airlock, he'd just enter the mod as the same 6 year old he was at the point when Daly stole his lollipop. Their goal was just to get out of their own hellish existence any way they could. Sure, they had absolutely no way of knowing Daly would be trapped (and would probably end up dead in the real world) as a result of their plan but as far as they were concerned, at least they'd be free and that was all that mattered to them.
Also, the point is to make it harder for him to do so. It's still going to take time and effort for him to recollect samples of DNA of the people he wants to torment. It's not perfect, perhaps, but they also have limited control over this situation and it's the best they can manage.