• The episode title, “Cracked Mirror”, follows the practice of referencing mirrors in titles of episodes where the mirror universe is visited, going back to the very first, “Mirror, Mirror”.

    • Prior to “Cracked Mirror”, there were eight mirror universe episodes, alluding to mirrors in the titles:

      • “Mirror Mirror”
      • Through the Looking Glass”
      • “Shattered Mirror”
      • “Reflections”
      • “In a Mirror Darkly, Part I”
      • “In a Mirror Darkly, Part 2”
      • “Mirrors” - this episode does not visit the mirror universe, but does largely take place on a mirror universe ship that transported refugees to the prime universe

    • There are nine mirror universe episodes that don’t mention mirrors in the title, as well as the “Section 31” film. This is not including “The Tholian Web” or “Into the Forrest I Go”, which do include the mirror universe, but one only as a retcon, and the other only in a cliffhanger for the following story arc.

• ”The protowarp is merely bending spacetime around us.” Zero’s vague explanation for how the protodrive works does not differentiate it from how the more common warp drive works: the ship generates a subspace displacement field which compresses spacetime in front of the ship, and elongates it behind. So is the protowarp merely a more powerful version of the warp drive?

• ”She’s a whole lot different than the one I remember.” We’re told the character of Chakotay served aboard the USS Voyager on VOY that was stuck in the delta quadrant in VOY, but I cannot find any indication of the character.

• The Emergency Janeway Hologram tells Rok-Thak she’s a dog person. Unlike Captain Archer, the real Janeway whom the EJH is patterned upon left her dog, Mollie, in the care of her fiancée when she took command of Voyager, as per “Caretaker”.

• Admiral Jellico has taken command of the USS Voyager A. Jellico was introduced in “Chain of Command, Part I” as the captain assigned to temporarily take command of the USS Enterprise D.

    • The Protogies quickly discover that they reality where Jellico takes over after the deaths of Janeway, Tysses, and Noum is an alternate to their own, so fortunately Jellico can’t make anything worse for them in a way that it matters.

• It’s Okona! From Star Trek! Or at least an alternate reality iteration of Okona. He’s outrageous! Okona was introduced in the episode “The Outrageous Okona”, and the Protogies previously met in him in season one’s “Crossroads”. Okona is voiced by Billy Campbell, who also portrayed him on TNG.

• When Rok-Thak and Zero exit the turbolift, they find the Voyager A crewed by Enderprizians, who were introduced in “All the World’s a Stage”. The ship

    • The Enderprizian whom Rok-Thak and Zero speak with activates his comm to alert Captain Tuvix.

• ”I’ve been through something like this before.” Chakotay may be referencing the VOY episode, “Shattered”, where Voyager was caught in a temporal anomaly, and he was able to move through different time periods on the ship until finding a way to resolve the issue.

• Maj’el proposes using an inverse tachyon pulse to seal the interphasic rift Voyager A is caught in. In “All Good Things…” it was discovered that the USS Enterprise D using inverse tachyon pulses at the same point across three different times is what was creating the anti-time eruption.

• It’s the Mirror Universe! From Star Trek!

    • MU Janeway is wearing a Starfleet uniform, though “Crossover” established that the Terran Empire fell to the Klingon Cardassin Alliance in the 23rd century. This could indicate that there is still a pocket of the Terran Empire active, which was the case in the Shattered Mirror comics.

    • Janeway’s uniform does appear to be based on one from the Shattered Mirror comics. Like the mirror universe Marshall Janeway from Star Trek Online, this iteration has a Borg implant similar to Seven of Nine’s over her left eye.

    • MU Chakotay has a goatee, a look popularized for mirror universe executive officers by Spock in “Mirror, Mirror”. MU Chakotay also sports the same tattoo as his prime universe counterpart. As per “Tattoo”, Chakotay got the tattoo to honour his father.

• Apparently humpback whales are able to serve in the Terran Empire as well, though that does raise the question of how humpback whales were able to survive being hunted to extinction in the mirror universe, considering they killed out in the prime universe. Were there circumstances similar to those of “Star Trek: The Voyage Home”? Or perhaps Terrans simply got more joy out of grinding up puppies, rendering whaling obsolete.