The title of the episode, of course, pretty much telegraphs which parallel universe we’re likely to have elements of this week. The Mirror Universe was a major part of Season 1 of DIS, and the Mirror Philippa Georgiou was a supporting character through the first 3 seasons.

The Stardate is 866282.9. I’ve said this a lot, but the new Stardate system baffles me. By TNG reckoning the 866000s should be 3189, but they confirmed it was 3191 in DIS: “Jinaal”, so how it’s calculated now is anyone’s guess.

Book browses through Moll’s records - the first one is from the Federation, the third from Andor. I don’t recognize the logo or alien script from the second one, although it vaguely reminds me of Alienese from Futurama.

Burnham quotes from a Kellerun (Rayner’s species) classic, The Ballad of Krul, “Serve it without a grum of osikod.” From context it probably means not to sugarcoat whatever is said next, with “grum” as a quantity and “osikod” either as a flavoring ingredient, or a word meaning deception, i.e. “without an ounce of bullshit.”

Book makes reference to charging impulse capacitant cells and then releasing the energy into the drive coils. Impulse engines, although limited to sublight operations, have had warp driver coils as part of their design in various eras. In the 22nd Century, according to the USS Enterprise Haynes Manual, the NX-01 used the inertial mass-altering capabilities of a warp field to increase the apparent mass of ejected propellant to achieve greater thrust. In SNW: “Memento Mori”, there is a reference to only half impulse speed being achievable with one warp nacelle damaged. The TNG Technical Manual says that as of the mid-24th Century and the designing of the Ambassador-class, driver coils were built into impulse engines to lower the inertial mass of the ship so that even at sublight the ship would be easier to push.

Book is aware of the Mirror Universe, since he recognizes the ISS prefix (as opposed to USS) for Empire ships. And we see it is the ISS Enterprise, last seen in TOS: “Mirror, Mirror”.

Michael says that crossing between universes has been “impossible for centuries”. This is a stronger statement from from what Kovich said in DIS: “Die Trying”, when he stated that the MU and the Prime Universe had been drifting apart ever since Georgiou crossed over (back in the 23rd Century), and there hadn’t been a crossover between the two for 500 years. While it’s debated, I’m of the school of thought that Georgiou did cross universes (and time) during DIS: “Terra Firma” thanks to the Guardian of Forever. And in that same episode, Kovich related the tale of Yor, a Time Soldier, from the 2379 of the Kelvin Timeline to the 30th Century of the Prime Timeline.

Cardassian voles are rapidly breeding pests that are attracted to energy fields. They are native to Cardassia Prime and first mentioned in DS9, but have made appearances in ENT and also DIS Season 1. DS9 once suffered an infestation of voles.

A graviton pulse was used to seal up a subspace rupture in TNG: “Schisms”. While the idea is to use it to stop the antimatter reactions making the aperture pulse, the 43.7% chance of implosion sealing it forever makes sense with what it was used for in “Schisms”.

The bridge of the ISS Enterprise uses the same set as SNW, but with the Empire logos and a ISS dedication plaque as part of the redress. Michael wants to use the sensors to track quantum signatures from “our universe”. It was established in TNG: “Parallels” that every possible universe has a unique quantum signature as does its inhabitants.

Michael mentions her mirror counterpart and how she must have died before ISS Enterprise was trapped. The exact disposition of Mirror Michael is unclear. in DIS Season 1 she was lost in a shuttle accident and Prime Michael posed as her. In the licensed comic book Succession, (co-written by novel and series writer Kirsten Beyer) it was revealed that Mirror Michael had survived and managed to ascend to the throne, but she was in turn killed by Mirror Airiam. In DIS: “Terra Firma”, Mirror Michael finally makes an on-screen appearance. Mirror Georgiou and her fight and kill each other before Georgiou is returned to the 32nd Century, so it depends on whether you believe Georgiou was actually traveling in time or not or whether she was in the actual MU or not. In any event, Prime Michael is unaware of the events of the comic or Mirror Georgiou’s time/space travel.

Michael looks at her adoptive brother Spock’s station - or at least where it would be on the Prime Enterprise. Despite Michael’s assumption, Mirror Spock was not exactly “as ruthless as the rest”. As Prime Kirk described him in TOS: “Mirror, Mirror”, he was a man of integrity “in both universes”. Sadly, it would be Mirror Spock’s reforms towards peace that would lead to the Empire being toppled by a Klingon-Cardassian alliance.

The intermix chamber is where the matter/antimatter reaction of the warp core takes place. In TNG times, the entire warp core assembly consists of the intermix chamber plus the matter and antimatter injectors and tubes which is what is jettisoned when they order the warp core to be ejected (VOY: “Day of Honor”, et al.).

The plaque in the transporter room indicates Tartarus Base on Stardate 32336.6 - by TNG reckoning that would correspond with 2355, but who knows how the Terrans measured stardates? In any case, since they’re using the SNW sets, the ship itself is apparently showcasing mid-23rd Century levels of technology. Oddly, for a plaque apparently put up by dissidents, it says "Long Live The Empire". Tartarus Prime was mentioned as a planet with high temperatures in the novel The Rings of Time.

The Terran High Chancellor making reforms might be referring to Spock, who was said to have risen to be Commander-in-Chief of the Empire (DS9: “Crossover”). Mirror Saru was a Kelpien slave in the MU experienced by Georgiou in DIS: “Terra Firma” but was saved by her and consequently went on to save a lot of lives. If the plaque was put up in 2355, then these events would have taken place about 97 years after Mirror Saru was saved by Georgiou and about 88 years after Mirror Spock met Prime Kirk. We don't really know how long Kelpiens naturally live, but Su'Kal (the one who caused the Burn) lived to be over 120 years old, so it's possible.

Interestingly, there are holoemitters in Sickbay, which seem to indicate later-24th Century technology (i.e. the EMH of VOY). Of course, this is all assuming tech levels are consistent across universes. I have many questions.

An Erigah is a Breen blood bounty, and we have a fan theory confirmed: L’ak is indeed a member of the mysterious Breen that have never been seen unmasked on screen. In the Litverse, the Breen are actually a society rather than a single race, consisting of six species, none of whom match L’ak’s description.

In the flashback, the Breen Moll meets wear similar uniforms (although the helmets don’t have the pronounced “beak”) and speak the same unintelligible language from their appearances in DS9. The Breen also carry what must be a 32nd Century version of the neural truncheons they had in DS9, which acted like cattle prods.

Moll identifies L’ak as the “Primarch’s nephew”. Coincidentally, in DS9: “The Adversary” the leader of the Tzenkethi Coalition in the 24th Century is known as the “Autarch”.

When L’ak first removes his helmet, his skin and skull are almost transparent, reminding me of how the Gallamites were described with transparent skulls and brains twice the size of humans (DS9: “The Maquis, Part 1”). It seems that Breen skulls and skin get more opaque with exposure.

Callor V was previously mentioned in DIS: “Jinaal”. Rubindium is used in communications tech, first mentioned in TOS: “Patterns of Force” and subsequently in DIS: “Far from Home”. There is also a similar-sounding element called rubidium (VOY: “Think Tank”).

The Emerald Chain, an organized crime concern, was the central antagonist in Season 3, but are shattered by the end of it, so that dates the start of Moll and L’ak’s relationship to 3189.

Booker’s planet Kwejian was destroyed by the DMA in Season 4, in case anyone forgot, leaving him the last of his species.

The Primarch says L’ak carries the genetic code of the Yod-Thot, “They who Rule”. In DS9, “Thot” denoted a high rank (the script for DS9: “Strange Bedfellows” describes Thot Gor as a Breen general). As a side note, the Klingon word yoD means “shield”.

So Breen have “two faces”, one transparent and one not. Hopefully we can get some backstory to explain why this is, and why the non-transparent face is viewed with disdain. The weapon the Primarch materializes is a sleeker version of the 24th Century Breen rifle.

We see L’ak apparently bleeding, although the fluid isn’t red. In DS9: “In Purgatory’s Shadow”, Bashir says Breen don’t have blood, although how he knows this for sure is not explained. While this could be misinformation, some Earth invertebrates have circulatory systems that contain, not blood, but hemolymph, a fluid that carries carbohydrates, lipds, amino acides, hormones, etc. through the body. The Breen could be similar.

Rhys’s suggestion seems odd at first blush - don’t photon torpedoes already have antimatter in them? Then you realize his idea is to replace the matter in the torpedoes with antimatter as well, adding more antimatter to the aperture reactions. I’m still trying to figure out why hexagonal.

Michael comments that “hit it,” sounds weird and sticks with her own “let’s fly.” Of course, “hit it” was Pike’s catchphrase to go to warp.

I’m going to leave the question of how Stamets is able to recognize that it’s the ISS Enterprise from this distance unanswered. The setting and ending of the episode was kind of spoiled if you had paid attention to the Season 5 trailers anyway.

The face off between the ISS Enterprise and the refit Discovery reminds me of a similar face off between the USS Enterprise and Discovery at the end of Season 1 (DIS: “Will You Take My Hand?”).

Michael used the tractor beam earlier to signal 3-4-1-4, a reference to The Ballad of Krul Section 4, Verse 7 where Krul calls to his war brother for rescue with a drumbeat using that pattern.

I’m still kind of bummed we didn’t see any Tzenkethi despite being in their space. Which kind of makes me wonder what their status is in the 32nd Century.

Culber refers to his death and resurrection in Season 1 (DIS: “Despite Yourself” and “Saints of Imperfection”, respectively).

We find out that the MU refugees did make it to the PU, and one of them, Dr Cho, became a Branch Admiral in Starfleet. Presumably the trauma of existing in a different universe wasn’t as severe because there was no time travel involved, unlike Yor or Mirror Georgiou, who crossed universes and had a centuries-long gap.

The Branch Admiral rank was detailed in the FASA Star Trek RPG’s TNG Officer’s Manual, and was a new rank to extend Admiral’s rank and privileges to non-Command division positions like the Starfleet Surgeon General, or other divisions like Security or Engineering, or the Inspector General’s Office. This was to give them the requisite authority to carry out their policies.

Since Cho was a part of Jinaal’s group, which existed during the Dominion War (2373-2375), that makes the Starfleet. Presumably the trauma of existing in a different universe wasn’t as severe because there was no time travel involved, unlike Yor or Mirror Georgiouears old, assuming she was commissioned at the same time as her Prime counterpart, in 2245. Which leaves the question of why the tech is the same despite nearly a century apart up in the air, since they apparently added holoemitters. Maybe the show should have used the Enterprise-D sets from PIC Season 3. The Enterprise-D was commissioned between 2362 and 2364 (sources vary), so that’s actually a closer date.

The dedication at the end is to Allan Roy “Red” Marceta, who was a lead set dresser on DIS. He passed away in 2022.