• Uhura provides the stardate 2398.3 in her communications officer’s log.

• Uhura is routing communications manually like a switchboard operator, because apparently every extra bit of computing power is necessary for an experiment Spock is running. Among the calls she takes are:

     • Captain Pike requesting a hail be put through to Captain Batel, who was introduced in the series premiere, “Strange New Worlds”.

     • Number One requesting an update on the arrival of James Kirk from the USS Farragut. James is Sam Kirk’s brother, who was introduced in the episode “Where No Man has Gone Before”. The Farragut was first mentioned in “Obsession”.

     • Chapel is awaiting a reply from Doctor Korby regarding her application to his fellowship. In “What Are Little Girls Made Of?” we find out that Chapel and Doctor Korby were engaged before he went missing on the planet Exo III in 2261.

     • Uhura’s console shows names and ranks of people whom are using the communications, though we only see named characters and ”cadet” who apparently doesn’t rank having a name. Interestingly, Number One’s is listed only as ”Lt. Una”, whereas characters other than Spock have their first initial and full surname; also, Number One’s rank is lieutenant commander, not lieutenant.

• We see lieutenant Mitchell in the captain’s chair, I believe for the first time.

     • When Pike arrives on the bridge later, Mitchell is back at navigation, and an unnamed gold shirt is in the big chair.

• The captain of the Farragut sent a message ahead of James’ arrival on USS Enterprise but we’re not given that character’s name. Previously, the ship was commanded by Captain Garrovick, but he was killed by a predatory cloud two years earlier than this episode, according to “Obsession”.

• The drink James mentions refers to the time La’an contacting under false pretenses after watching an alternate universe doppelganger of him get killed by a Romulan agent in the past in “Tomorrow and Tomorrow and Tomorrow”.

• Doctor M’Benga echos the claim Spock makes in “What Are Little Girls Made Of?” that Doctor Korby is ”the Louis Pasteur of archaeological medicine.”

• The song Uhura sends through the subspace fold is “Anything Goes”, written by Cole Porter for the 1934 musical of the same name. The version she selects was recorded by Eileen Rodgers in 1962.

• Spock begins singing his report, and is followed by the rest of the cast, for “Status Report”. The first time we saw a character sing in Trek was in “Charlie X” when Uhura sings in the rec room.

• The opening credits are accompanied by an a capella version of the theme.

• The Heisenberg compensators are a transporter component introduced in “Realm of Fear”.

• During the song “Connect to Your Truth”, Number one sings, *”I can see myself up on the stage, And for three hours a night, And to everyone’s delight, I’d regale them all with my renditions, Of Gilbert and Sullivan.” While trapped in a turbolift with Spock in “Q&A” the pair sang a piece of the “Major-General’s Song”.

     • The theme of the song is based in Number One’s new philosophy that she should not be so closed off from the crew, though in “Q&A” she advised Spock that it was necessary ”keep [his] freaky to [himself]” if his ultimate goal was command.

• While she sings “How Would That Feel” La’an opens a case in a drawer in her quarters to reveal she’s held on to the diver’s watch she and the alternate James Kirk used in “Tomorrow and Tomorrow and Tomorrow”.

     • In her fantasy, we see the hotel room she and that James shared, which he was able to pay for in cash after winning a bunch of chess games.

• During “Private Conversation” we learn that Captain Batel’s first name is Marie. Surely this, and the sudden priority one mission the USS Cayuga is assigned at the end of the episode can only mean good things for her long term prospects as a character.

• The improbability field causing the Enterprise crew to break out into song is expanding to the entire fleet, including the USS Cayuga. Uhura projects a map of the local subspace network on the main viewer, and in addition to the Enterprise and the Farragut we see listed:

     • USS Lexington; Constitution-class - first seen in “The Ultimate Computer” but listed on a chart of ships at Starbase 11 in “Court Martial”

     • USS Potemkin; Constitution-class - first seen in “The Ultimate Computer”

     • USS Kongo - only listed on a chart displayed in “Star Trek: The Undiscovered Country” and named on the pin Spock wore for Starfleet Remembrance Day in “Memento Mori”.

     • USS Republic - James is mentioned as having served aboard the ship in “Court Martial”

     • USS Hood; Constitution-class - first seen in “The Ultimate Computer” but listed on a chart of ships at Starbase 11 in “Court Martial”

     • USS Valiant; Valiant was one of 14 names proposed for Constitution-class ships by the producers of TOS’ second season

• ”...And those feelings pose an actual space-time security risk.” La’an is referring to the events of “Tomorrow and Tomorrow and Tomorrow”.

• *”The secrets I keep safe inside, A skill I perfected, So I could survive.” During the song, “Keeping Secrets”, Number One refers to the fact that she previously hid the fact that she’s an Illyrian, and subject to prejudice and discrimination in the Federation.

• ”The last thing anyone wants is singing Klingons.” Klingons have a rich history of opera and drinking songs.

• General Garkog is played by Bruce Horak, who has previously portrayed Hemmer in season one, and the illusion of Zombie Hemmer in “Lost in Translation”.

• “Some of us need fun to deal with the constant threat of dying.” Kirk is killed by flying extragalactic parasites on the Deneva colony after leaving Starfleet, and his corpse is found in “Operation -- Annihilate!”

• During “I’m Ready” Chapel sings, “The sky is the limit, My future is infinite, My possibilities are endless.” Chapel continues serving aboard the Enterprise for over a decade, eventually becoming and MD and taking over as chief medical officer until Kirk has Doctor McCoy drafted in “Star Trek: The Motion Picture”. She does not appear to be part of the crew when the ship is reassigned as a training vessel, but does show up organizing relief efforts on Earth during “Star Trek: The Voyage Home” when the whale probe begins to destabilize the planet.

• La’an calls the incoming Klingon vessel a K’t’inga-class ship. The term originated in Gene Roddenberry’s novelization of “Star Trek: The Motion Picture”; this is actually the first time it’s been said on screen.

     • The model we see is the same as the one used for the D7-class introduced in “Through the Valley of Shadows”. Whether or not the K’t’inga and the D7 are the same ship has been a matter of some dispute among fans since 1979, and this likely isn’t to change that.

• James mentions his baby mama, Doctor Carol Marcus, who was introduced in “Star Trek: The Wrath of Khan”.

     • Doctor Marcus is pregnant with their son, David Marcus, which would mean he’s around 25 years old when he appears in “Star Trek: The Wrath of Khan”.

• Spock sings “I’m the X”, as song about how he needs to close himself off from his emotions to avoid being hurt in relationships. In “This Side of Paradise” he encounters Leila Kalomi, a woman who fell in love with him six years earlier in 2261, but he never expressed his feelings to her.

• In “Keep Us Connected” Uhura recounts how everyone around her dies, beginning with the deaths of her family via shuttle crash, which we learned about in “Children of the Comet”, and then Hemmer’s demise in “All Those Who Wander”.

• Spock asks how they’re going to get 200 crew members to sing in spontaneous unison. The Enterprise had 203 crew people during their visit to the Talos system according to Pike in “The Menagerie, Part I”, as well as Burnham’s scans of the ship in “Brother”.

• During “We Are One”:

     • James sings, “If I make captain, It’ll be thanks to all of you.” Seems like he’s getting a little bit ahead of himself.

     • We see the interior of the IKS par’Machstreet Boys, and it is significantly different from any Klingon bridge we’ve seen before, including being extremely deep, as well as having a captain’s chair that appears capable of dollying backwards.

     • The Klingon captain’s chair has Klingon glyphs on it, which appear to read “Kahless Rocks”.

     • The mek’leths the Klingons are dancing with are the simpler version originally introduced in “The Way of the Warrior” as opposed to the more ornate iterations seen in season one of DIS, beginning with “Battle at the Binary Stars”.

• Spock once again was able to drink the Klingons into not wanting destroy the Enterprise, as he did in “The Broken Circle”. This is not a technique he employed in other encounters with the Klingons, such as in “Errand of Mercy”, “Friday’s Child” or “Day of the Dove”.

• ”Sorry, earworm.” In “Star Trek: The Wrath of Khan”, Khan inserted Ceti eel larva into the ears of Captain Tarrell and Chekov, causing them to be extremely susceptible to suggestion.