The Husbands of River Song (TV story)

The Husbands of River Song was the 2015 Christmas Special of Doctor Who. It was written by Steven Moffat, directed by Douglas Mackinnon and featured Peter Capaldi as the Twelfth Doctor and Alex Kingston as River Song.

It was the show's eleventh Christmas special since its revival and the second Christmas special starring Capaldi as the Doctor.

This Christmas special uses the formula from Silence in the Library/Forest of the Dead but in reverse; River is clueless about the Doctor's identity until near the end of the episode, which mirrors how the Doctor didn't know who she was when they first met. Their apparent ages are also reversed, when the Doctor first met River, he was the younger Tenth Doctor; this time, the Twelfth Doctor appears older than River.

It was noteworthy for closing the book on River Song's timeline that began with her debut. It also showed the Twelfth Doctor's first encounter with River. For River, this was the final adventure with the Doctor before she met her demise in the two-part television story Silence in the Library / Forest of the Dead. This episode also showed the Doctor turning up on River's doorstep with a new haircut and a suit, their night on Darillium to see the Singing Towers, and the Doctor giving River his sonic screwdriver, all of which had been previously mentioned by River in the character's debut story.

In The Time of Angels, River stated that she had seen "all [the Doctor's] faces". This is proven true, for the Doctor's original regeneration cycle at least; this even included a picture of the War Doctor, whom the Ninth, Tenth and Eleventh Doctors all tried to keep buried in their memories of the Time War. It also makes a subtle reference back to Journey's End, where the Doctor used a full regeneration, his eleventh out of twelve to create the Meta-Crisis Tenth Doctor and DoctorDonna. Thus River thought the Doctor only had twelve incarnations.

The Doctor takes River's assistant, Nardole, with him after this story as his companion. River's passing would also continue to haunt the Doctor for some time, right into the next year's Christmas special The Return of Doctor Mysterio.

Synopsis
The Twelfth Doctor is on the planet Mendorax Dellora in 5343, where he is asked by a man named Nardole to follow him, thinking he is a surgeon, on the orders of River Song. A surgeon is required to remove a diamond from the head of the tyrannical King Hydroflax. It became lodged there due to a ruthless act of thievery gone wrong, and River seeks to recover it. Surprised that River cannot identify his newest face, the Doctor struggles to break the news to her while learning how she acts on her own - and how many other lovers she has had. However, both he and River soon find that the time is drawing close for the last page in the diary of their journeys together to be written...

Plot
On Christmas Day, 5343, on the human colony of Mendorax Dellora, a man named Nardole is searching through a town for something pictured on a piece of paper. He comes across the TARDIS, believing he's found what he was sent for; he knocks on the door, which has a sign saying "Carolers will be criticised." The Doctor opens the door, asking if there is something on his head; Nardole confirms that there are antlers on the Doctor's head. Closing the door, the Doctor yells at the TARDIS for trying to cheer him up with holographic antlers.

An electronic hum comes from inside, and the Doctor thanks the TARDIS for listening to him. The door opens again, with the Doctor now lacking the antlers; he asks what Nardole wants. Nardole asks if he's a surgeon. The Doctor tells him that's close enough, inquiring if he needs one. Nardole confirms this and begins walking away. He turns back to see the Doctor hasn't moved. The Doctor asks if there will be carolling where the emergency is, to which Nardole denies. Happy there will be no singing, the Doctor exits the TARDIS and locks the doors.

The Doctor follows Nardole through town. Nardole explains they weren't sure where his "capsule" would land. The Doctor says it's a common thing for him, before stating he's had a bad day of "people turning into lizards" and a piano falling on him. Moments after they pass someone, an elderly man with a bag approaches and asks the person if they were looking for a surgeon.

Nardole brings the Doctor to a crashed spaceship. A cloaked woman exits the ship, asking who the Doctor is. Noting the Doctor does not look like the surgeon's photos, the Doctor jokes that it's an on-going problem. Sensing that the woman is familiar, the Doctor asks if they've met. She states they have not, removing her hood to reveal herself as River Song. Smiling, the Doctor says her name. River is shocked he knows her name, asking how he knows her. The Doctor laughs, stating it would take a flowchart; however, River doesn't take the hint. Nardole tells the Doctor that he must refer to her as Dr Song, or Professor Song. Annoyed, River tells them to never speak her true name again or she will remove their organs in alphabetical order. Amused, the Doctor asks which alphabet. River scowls and heads back inside the ship.

Heading inside, the Doctor asks what the emergency is. River states that it's her husband. The Doctor is shocked, asking her to repeat that. River responds that her husband is dying. Stopping in his tracks, the Doctor is asked by Nardole if he's alright; the Doctor states "I'm going to need a bigger flowchart."

River leads him to her dying husband, King Hydroflax. To the Doctor's disgust, Hydroflax recalls having many romantic nights with River. Due to the guards being genetically-engineered to have anger problems and sentient laser swords, Nardole tells the Doctor to not do anything upsetting, like crossing his arms; the Doctor tells Nardole that he's got cross arms, crossing them anyway. River then tells Hydroflax that she called in the best surgeon in the universe to save his life. The Doctor quietly tells Nardole that he made a mistake and not to "make puddles". Seeing he has no choice but to help, the Doctor approaches to study the patient, being told to bow in the king's presence. However, the Doctor states he cannot do so because of his back. The Doctor examines Hydroflax, determining that something is jammed in his head. River takes him to an adjacent room to discuss the operation.

River shows the Doctor a holographic x-ray of Hydroflax's head, which reveals that the Halassi Androvar, the most valuable diamond in the universe, has become lodged in Hydroflax's brain during a raid on the Halassi Vaults and is slowly killing him. Having been hired by the Halassi to recover the lost treasure, River posed as Hydroflax's nurse and pretended to love him; took less than a week for Hydroflax to propose to her. According to River, men will believe any story they are the hero of. River tells "the surgeon" to remove Hydroflax's entire head, considering it quicker and easier. "I'll kill the lights; you kill the patient." The Doctor is shocked, wondering if this is what she's like without him to keep her homicidal tendencies in check. He states that he'll decide what needs to be done because he's the Doctor; however, River doesn't get this obvious hint. She says he reminds her of someone; the Doctor starts to describe his last incarnation, but River exclaims that it's her second wife that he reminds her of.

They are surprised by Hydroflax, who has listened to their conversation. Hydroflax tells them that if they wanted his head, they should have just asked, promptly removing his head from his body; Hydroflax is truly nothing more than a head on a mechanical body. River notes she thought it was strange they never shared a bathroom. He demands to know who his wife really is; River tells him that she's Professor River Song, archaeologist hired to retrieve the diamond and give back to the people he's taken so much from. She's even got a sonic trowel. The robot body begins closing in on River and the Doctor per Hydroflax's orders. However, River threatens Hydroflax's head with her trowel, causing the body to halt. Despite Hydroflax ordering his body to attack, its AI tells him to chill as there is a high probability Hydroflax will be harmed. River shoves Hydroflax's head in a gym bag she has, despite his protests that it smells; she radios her contact Ramone, to teleport her and the Doctor.

The two end up a foot above the snow and fall. Annoyed, River radios Ramone, telling him to work on the landings. Hearing Hydroflax threaten them, the Doctor bursts out laughing. River tells him it's not funny; however, the Doctor points out the ridiculousness of being threatened by a bag. They both laugh as Hydroflax continues to yell threats. The Doctor now thinks River was just messing with him, asking if she really does know who he is. River states that she does not, as Ramone arrives; River pulls him into a kiss. The Doctor wonders "doesn't [kissing] get boring? It's not a varied activity." River reveals Ramone is another of her husbands, whose memory she wiped of their marriage because he was getting annoying. The Doctor sarcastically asks if she's going to murder him as well.

Ramone informs River that he has not found Code Name: Damsel in Distress, despite his capsule being in the village. River asks Ramone if he's sure as he has twelve faces. Ramone unfolds twelve pictures, which are of the First, Second, Third, Fourth, Fifth, Sixth, Seventh, Eighth, War, Ninth, Tenth and Eleventh Doctors; he adamantly states that none of these men are in town. River is flabbergasted as she crashed Hydroflax's ship in this location because it's where she had the best chance to meet up with the Doctor. Deciding to tease River, the Doctor states that he may have a face she doesn't know about; knowing the Doctor wasted a regeneration, River states that he has "limits."

Onboard Hydroflax's ship, his robot body decides to upload information about River Song from Nardole; it does so by decapitating him and placing his head in place of Hydroflax. It now has the information about where the TARDIS is located and that River is known to be associated with it.

The Doctor follows River and Ramone to the TARDIS, where River states she'll just borrow it. Taken aback by this, the Doctor notes that "Damsel" sounds dangerous and might be angry with her for stealing his ride. River states that he's never noticed before when she borrowed the TARDIS and put it back where it was before, so why would she worry about it now. Aggravated to hear this, the Doctor states that he'll start noticing NOW. River sends Ramone off to get ready for their beach holiday. She heads inside, telling the Doctor that it's not as snug as it seems inside. Seeing it's "his turn" to play the shocked companion, the Doctor pretends to be shocked by the "bigger on the inside", giving, in his opinion, a better monologue than others. The Doctor is then shocked to see that River turned one of the roundels into a cupboard for alcohol.

Outside, Ramone is heading back to his own ship to head to his vacation spot to wait for River. He hears Nardole calling for help. He finds the robot holding Nardole at gunpoint. Confused, Ramone asks why Nardole is aiming a gun at himself. Nardole states he's not, it's the artificial intelligence controlling the robot. The robot demands that Ramone deliver a message to the former queen River Song. Ramone asks what the message is that he's supposed to deliver.

Inside the TARDIS, River preps things for taking off; the Doctor suggests several buttons, which she explains actually don't help to fly the TARDIS. The Doctor learns to his shock that one button actually causes the waste tanks on Deck 7 to be released. Deciding to avoid Deck 7 for a while, the Doctor watches as River tries to take off; however, the TARDIS refuses to budge. With her confused, the Doctor reveals that the "real-time" envelope cannot be sealed as the TARDIS registers Hydroflax as inside and outside at the same time, due to the head's life-support being connected with the robot body. Being called good for a doctor, the Doctor is annoyed River still hasn't figured it out.

A knocking is heard on the door, with Ramone yelling for River. River opens the door to find Ramone's head on the robot body; apparently, the robot's answer to everything is to cut off someone's head and use it. It starts attacking, with the Doctor grabbing Hydroflax's head. He threatens to send Hydroflax down the trash chute if he doesn't "get himself under control." This works, with River piloting the TARDIS to land in the starship Harmony and Redemption. To the Doctor's surprise, River pulls his hand instead of the other way around, leading him out of the baggage area and shutting the door behind them.

River meets the Maître d', Flemming, who has met her before; apparently, his children have eaten their mother in a "lovely ceremony" and are still digesting her. River asks him to deadlock seal the baggage hold, reminding him of the trouble it caused when he didn't during the last time when she was transporting dragon eggs. Haunted by the very memory, Flemming tells her it will be done; the doors are locked just as the robot pounds on them to get out.

Flemming asks if the Doctor is here for dinner, which River confirms; he grabs the Doctor, saying that he'll have the cooks prepare him immediately. However, the Doctor stops him and River explains that he will be joining her for dinner. Flemming tries to pass off his blunder as suggesting her guest would need to be force-fed. Flemming leads them to the dining room, hearing Hydroflax's muffled yells. The Doctor passes it off as his stomach being upset.

River stops, stating she needs to change her clothes. She takes out a perfume bottle and sprays herself, turning her clothing into a dinner gown. "Not bad for 200, eh?" River smirks. The Doctor is taken aback by this; even though River has some Time Lord DNA, she is still mostly human and therefore should not have been able to live this long. River explains that she had her lifespan augmented. Taking a drink from a serving tray, River explains that the ship is full of people like her or worse. Suites are reserved for world destroyers. Even the staff need a provable history of indiscriminate murder. "This is where genocide comes to relax. Do try the fish."

In the dining room, River reads her diary as the Doctor fidgets nervously. The Doctor notes deadlock seals can be broken; "by geniuses" River retorts, and a robot body isn't going to be one. He inquires as to why they're there, to which River says she's waiting for the person who answered her advert for selling the Halassi Androvar. The Doctor is surprised, wondering why River would do this when she was hired to bring it back to the Halassi. Laughing, River asks if the Doctor was born boring or he had to work hard to be so. Seeing River frowning at her diary, the Doctor asks if it's a sad story; she notes the one who gave it to her knew how long it should be, and there are only a few blank pages left for her to write in.

A man with a large scar across his face walks up to them asking for Song. Introducing himself as Scratch, a representative of Shoal of the Winter Harmony, he is silenced by River, who asks if he's empowered to purchase. They squabble over showing the merchandise or the payment. Scratch pulls the right side of his head open, removing an orb; disgusted, the Doctor tells him that he shouldn't be doing that where people eat. Scratch explains that the orb connects to every bank in the universe; once given commands, it will give River any amount of payment she desires. Happy, River gives him the bag, telling Scratch he might need a spoon to dig for the diamond. Annoyed, Scratch reveals that he filled the meeting point with members of his own species to ensure honest transaction.

In the meantime, Flemming is informed by another member of the staff of a situation in the baggage hold. Ramone appears on the monitor, stressed and demanding to be let out; unknown to Flemming, the robot body is holding a gun to his head off-screen. Flemming decides to go down and check things, getting held hostage by the robot body. It wishes to take his head for new information, but Flemming offers to give the body a head fit for a king instead.

Back in the dining room, River and the Doctor discover that Scratch and his compatriots worship King Hydroflax and are after the diamond in his honour. Despite attempts to hide the bagged head containing the diamond, they are forced to reveal the truth to create a distraction. Though it's considered heresy to try paying for the king, the Doctor laughs; "He can't be much of a king if you can't put a price on his head." They toss Hydroflax away and flee, only to be stopped by Flemming. The robot body enters, with Hydroflax happy he will be whole soon; however, the body stops short and scans him. The brain damage is now beyond recovery. Hydroflax orders his body to do whatever it takes to save him; it comes to the wrong conclusion that it needs a new head and disintegrates Hydroflax, leaving the diamond behind.

Flemming takes River's diary, explaining it is a guide to the best replacement head in the universe: the head of the Doctor. Scratch backs this up as the Doctor is a legendary being with multiple faces, which would be Hydroflax's crowning achievement. Flemming reads the diary, noting River's been to Asgard for a picnic, the crash of the Byzantium (which was turned into a movie), has met Jim the Fish (who is known by everyone in this era) and has just been to Manhattan (which Flemming thinks is a planet). River is asked for the whereabouts of the Doctor, to which she truthfully doesn't know. The robot confirms it with a scan. However, Flemming believes that putting the Doctor's consort in danger will draw him in. However, River snaps at him; though she loves the Doctor, he never once said that he loved her. River tells them to scan for two hearts and stupid clothes, but they won't find him. The Doctor tries telling River who he is, but stops when River tells them the Doctor is above falling in love; "You don't expect a sunset to admire you back. When you love the Doctor, it's like loving the stars themselves." She then adds that he wouldn't be sentimental enough to be stuck in this situation with her. Breathing heavily from venting her feelings, River notices the Doctor's steady gaze and mild smirk. She gives a confused look, to which he says "Hello, sweetie."

Seeing how dense she's been, River tells him he'll be doing his roots, as the Doctor taunts her with the romantic poetry she used to describe her love for him; she then tells him she was just buying time until "it" happens. The robot body tells them to stop talking but is ignored. River asks the Doctor where the safest place would be if a meteor strike were to hit, and the Doctor tells her right where they are as it doubles as an escape route. Flemming asks what she means as the speakers announce the meteors' arrival; he asks River how she could have known. Smiling her usual smirk, River tells him that she's the archaeologist that dug his remains up in the future. The meteors hit and the floor gives way, allowing the Doctor and River to flee into the lower floor.

River tells the Doctor that she bought a guidebook that tells her when a restaurant will be destroyed; therefore, as a time traveller, she can get a free meal, as long as she doesn't go to the same place twice and create a paradox. The Doctor asks River if she likes his new body, to which she says she hasn't seen properly yet; however, she then wonders how he has a thirteenth one, as he ran out of regenerations. He tells her that "a thing" happened, to which she knows is usual with him. The diamond falls down towards them, with River catching it in her dress.

Hydroflax's body arrives to take the Doctor's head; the Doctor tells River to go stop the crash while he deals with this moron. The robot body cannot comprehend that even if it gets the Doctor's head, it won't survive the crash. Seeing the orb Scratch gave River, the Doctor grabs it and tells the robot that all kings need money. It demands he demonstrate. With a manic smile, the Doctor attaches it the base of the robot's neck and the A.I. begins sputtering randomly. "Welcome to the best firewalls in the universe. Nothing is protected like money." The robot garbles that it doesn't understand, to which the Doctor says is the same for everyone else. "He had a bad day at the bank." the Doctor tells an employee as he laughs at his own jokes and runs to join River.

In the bridge, the Doctor finds the crew has gone and River working at the controls. They start arguing over the marriages that the other had; the Doctor married Marilyn Monroe and Cleopatra, while River married Hydroflax,. Ramone and Stephen Fry. While the ship is crashing, River realises that they are heading towards the planet Darillium. River remembers that he always promised to take her there to see the Singing Towers, but always cancelled at the last minute. The Doctor retorts "I'll make sure to give them a wave as we pass by." Trying to save River, the Doctor tricks her into being teleported back to the TARDIS. However, she pilots it back to him. As they have entered the planet's atmosphere, they give up on saving the ship and take shelter in the TARDIS. The resulting impact of the crash knocks River unconscious.

Seeing that the universe is telling him to finally have his last night with River, the Doctor decides to give in to the inevitable. After travelling to the next morning, the Doctor suggests to a man searching for survivors of the crash that he builds a restaurant where they're standing, with a view of the Singing Towers, and gives him the diamond to fund its construction. Travelling forwards in time once again, the Doctor enters the now-built restaurant and books the table on the balcony for Christmas Day in four years' time. The Doctor doesn't mind as he can just jump to the date of his reservation.

When River awakes, she exits the TARDIS and is told by the receptionist that the Doctor is waiting for her. Changing for the occasion, River asks if they have a good table, to which she is told is the best in the house. To her shock, River runs into Hydroflax's body, now peacefully controlled by the heads of Ramone and Nardole; thanks to the Doctor attaching the orb to the robot, the A.I. was deleted in a bank merger. The body was pulled from the wreckage and the two of them have been working as a waiter in the restaurant since then. River shows attraction to Ramone's new body but is told to calm down by the Doctor, who has arrived in a new suit.

River compliments him, to which the Doctor tries to return the favour. However, River notes that her husband never knows when she looks good, but it was kind of him to try; at best, the Doctor has only noticed that River's hair has moved around a bit. The Doctor gives her a box, stating it's Christmas; River notes that the Doctor has never given her a gift before.

To her surprise and joy, it contains the sonic screwdriver she will use in the Library; "I saw the sonic trowel, and thought it was embarrassing." The Doctor demonstrates it to River, discretely scanning her into the neural relay hidden in it, so his tenth incarnation can upload her data ghost into the virtual world in the Library computer. River laughs with joy, as the Doctor hands her Christmas present back to her. The Doctor leads River to the balcony, which has an amazing view of the Singing Towers.

River listens in awe to the beautiful music. She then notices the Doctor is crying, something he blames on having the wind in his eyes. The Doctor states that it is the wind blowing through the crystal formations inside the towers that causes the music, according to some legends. He asks why River is ignoring the Towers, to which she sadly says "[you're] ignoring me." River reveals that her diary is nearly full, and asks whether the stories that this will be their final night together are true, to which the Doctor only responds by saying; "Spoilers", after knowing River for so long he had finally caught up with her in his timeline, and can't bring himself to reveal that this would indeed be their final night together.

River begs him to find a way around this event, but he insists there's no way to avoid the end of their times together and refuses to tell River the future. They both discuss the fleeting nature of things, River pointing out that "happily ever after" does not mean "forever", just "time"; it doesn't have to be much, just a little extra. Fearful that not much time is left before they part, River asks how long a night on Darillium is. Smiling, the Doctor informs her that one night on Darillium lasts for twenty-four years. Overjoyed, River once more tells the Doctor, "I hate you." He again replies, "No, you don't," As the two smile at each other

The words "And they both lived happily ever after" are displayed on-screen. Little by little, the message dissolves into gusts of snow, becoming more truthful as it gets reduced to "And they both lived happily", then only "happily", until it has all been swept away.

Cast

 * The Doctor - Peter Capaldi
 * River Song - Alex Kingston
 * Nardole - Matt Lucas
 * King Hydroflax - Greg Davies
 * Ramone - Phillip Rhys
 * Flemming - Rowan Polonski
 * Scratch - Robert Curtis
 * Concierge - Anthony Cozens
 * Alphonse - Chris Lew Kum Hoi
 * Receptionist - Nicolle Smartt
 * King Hydroflax's Body - Liam Cook
 * Voice of Hydroflax - Nonso Anozie

Uncredited cast

 * Starline Galactic Villain - Clem So

The Doctor

 * The Doctor mentions that his eleventh incarnation had a big chin.
 * River Song suggests that the Doctor would not approve of alcohol aboard the Doctor's TARDIS, or would not approve of her taking the alcohol while she borrows the TARDIS.
 * The Doctor still enjoys mocking archaeology, referring to River's sonic trowel as "just embarrassing".
 * The Doctor mentions Euclidean geometry.

River Song

 * River states that the Doctor has planned to take her to Darillium numerous times but has always cancelled at the last minute.
 * River references her father, Rory Williams, by pointing to her nose (Rory had a prominent nose) and stating "Don't tell dad" while offering alcohol to the Doctor.
 * When searching through her bag at the beginning of the episode, River pulls out a red fez. The Eleventh Doctor was fond of fezzes, thinking they were cool.
 * River Song owns the book History's Finest Exploding Restaurants with the tagline "The Best Food for Free, Skip the Coffee". She used it as a source when plotting her escape from the meteor strike that hit the Harmony and Redemption.
 * River has a unique perfume spray that lets her change her clothes as she pleases.

The TARDIS

 * The roundels are once again used for storage purposes. In this instance, alcohol is inside a cupboard behind one of them.
 * The TARDIS is able to produce a pair of hologrammatic antlers for the Doctor.

Technology

 * The body of Hydroflax contains a split quantum actualiser, thus its power source is a perpetually stabilised black hole.

Sonic equipment

 * River Song owns a sonic trowel, as a reference to her being an archaeologist. Her paternal grandfather, Brian Williams, habitually carried a regular trowel wherever he went.
 * The Doctor gives River her own sonic screwdriver, which she will eventually take with her to her investigation on the Library.
 * The Doctor uses his sonic sunglasses and his new sonic screwdriver.

Music

 * At the restaurant on Darillium, a string orchestra plays "The First Noel".
 * "Hark! the Herald Angels Sing" is played on Mendorax Dellora.
 * When River and the Doctor are in the dining hall on the Harmony and Redemption, Richard Wagner's Siegfried Idyll can be heard.

Locations

 * The Harmony and Redemption intends to visit the Andromeda Galaxy next.
 * The Singing Towers of Darillium "sing" due to the flowing of wind through the numerous cave structures in the towers which harmonises with the crystal layer.
 * There are 4 billion people on Mendorax Dellora.
 * As their name suggests, the Shoal of the Winter Harmony are originally from Winter Harmony.

Story notes

 * This is the first episode of Doctor Who since the 2012 Series 7 episode The Angels Take Manhattan, and the first starring Peter Capaldi, to not feature Jenna Coleman as Clara Oswald.
 * Gary Russell previously attempted to have the Twelfth Doctor and River meet in his novel Big Bang Generation, but as Steven Moffat set up The Husbands of River Song to be the Twelfth Doctor's first, last and only meeting with River before she sacrificed her physical body, Russell chose to replace River with Bernice Summerfield in the story.
 * This is the first Christmas episode to have no scenes take place on Earth.
 * This is the first time in a main story that Alex Kingston's name has appeared in the opening titles.
 * When River's sonic screwdriver is revealed as her present, an excerpt of the Series 4 soundtrack "Silence In The Library" is heard, foreshadowing the events to come in River's last adventure.
 * As Mels, River used the phrase "penny in the air" when someone was oblivious to something important, following up with "and the penny drops" when they finally figured it out, seen in TV: Let's Kill Hitler. Ironically, River is guilty of becoming the butt of her own joke for being oblivious to the fact that the Doctor is right in front of her until it is made indubitable.
 * This is the first time outside of mini-episodes that River has been in a story not to feature one of the Doctor's companions alongside her and the Doctor.
 * The little town set used for Mendorax Dellora appears to have been repurposed from the trap street set used in TV: Face the Raven.
 * A variation of The Doctor's Theme is played when River and Ramone discuss the "Damsel in distress".
 * No cast details accompanied the programme listing in Radio Times, which had the synopsis "When a crashed spaceship calls upon his help, the Time Lord finds himself launched on a chase across the galaxy. Greg Davies and Matt Lucas guest-star." However, the listing for the repeat on Boxing Day included a cast list as well the same synopsis but excluded the final sentence.
 * This is the first episode where both the Doctor and his companion are played by people over the age of 50.
 * River's pictures of the Doctors are screencapped from The Smugglers, The Two Doctors, Carnival of Monsters, The Hand of Fear, Resurrection of the Daleks, Mindwarp, Survival, Doctor Who, The Day of the Doctor, The Parting of the Ways, The Runaway Bride and The Bells of Saint John. 
 * The Doctor is heard to say "when the wind stands fair and the night is perfect, when you least expect it, but always when you need it the most, there is a song". Though he is referring to the Singing Towers in this context, his statement could also apply to River herself, either symbolically or as a compliment. This is due to his inclusion of the word "song", which is her last name. Moreover, "song" is another name for "melody", which the towers produce; River's birth name is Melody Pond, and her alternate name, River Song, is the result of her birth name being translated into the language of the Gamma Forests, seen in TV: A Good Man Goes to War.
 * The opening titles to this episode have several modifications. The cogs are accompanied by snowflakes. Like in TV: Last Christmas, the clock tunnel is icy, the names for the actors and show title appear/dissipate into snowy particles, the emerging rings have snowflake decals, and the TARDIS is covered in snow, except this time, the snow does not disappear mid-way into the sequence. The planets are also replaced by Christmas baubles.

Production errors

 * When King Hydroflax's talking head is resting on the console's telepathic panel, the panel is bending inward. When his head is removed, the TARDIS console is fine again. This is most likely due to the production staff having replaced the panel with a fake one, which would accommodate Greg Davies' head with comfort.

Ratings

 * BBC One Overnight: 5.77 million (29.4% overall audience share)
 * BBC America Overnight: 1.70 million
 * Final UK ratings: 7.69 million

Myths

 * A fragment of Rigsy's portrait of Clara Oswald, which disintegrated at the end of TV: Hell Bent, is visible on the TARDIS door. Inconclusive: some viewers claim it can be seen, but it could also be snow. A special TARDIS panel was created for the portrait (and later featured in the Doctor Who Experience exhibition), whereas the regular TARDIS shell would have been used for filming the episode.
 * Clara Oswald would appear. False. Originated from speculation that Jenna Coleman might have filmed a scene before completing her work on Series 9, similar to how Matt Smith filmed his cameo for TV: Deep Breath.

Filming locations

 * to be added

Continuity

 * Nardole calls River "Doctor Song", (TV: The Time of Angels, The Pandorica Opens, Closing Time, The Angels Take Manhattan) stating that she is also sometimes called Professor, (TV Silence in the Library, Forest of the Dead, The Angels Take Manhattan) but mainly Doctor, Song.
 * River tells King Hydroflax that he has "stolen so much from so many." When talking to the Eleventh Doctor about how much he means to her and the universe she gives a similar statement, that he has "done so much for so many." (TV: The Wedding of River Song)
 * Once again, someone comments on the TARDIS being bigger on the inside. (TV: An Unearthly Child, et al.) This time, it is the Doctor himself to an oblivious River, doing so sarcastically.
 * River mentions her history of escaping. (TV: The Pandorica Opens, A Good Man Goes to War, The Wedding of River Song)
 * The Doctor quotes River by saying "Hello, Sweetie" and "Spoilers". (TV Silence in the Library, et al.)
 * The Doctor uses his new sonic screwdriver. (TV: Hell Bent) He also uses his sonic sunglasses. (TV: The Magician's Apprentice et al.)
 * River owns a set of pictures of the first twelve incarnations of the Doctor, which she reveals to clarify that she knows what he looks like. She told the Doctor once that she had pictures of all his faces. (TV: The Time of Angels) This also confirms that River is aware that the War Doctor exists whom the Doctor once tried to conceal, as she has a picture of him as well. (TV: The Name of the Doctor)
 * River's picture set of the Doctor's first twelve incarnations creates a continuity error, in that her first appearance, she questions the Tenth Doctor about adventures she had with the Eleventh. The pictures in her collection are in exact chronological order, contradicting the idea that she mistook the Tenth Doctor for a later incarnation because she did not know the correct order of his regenerations.
 * When arguing about their other relationships, River Song holds against the Doctor his marriages with Elizabeth I (TV: The Day of the Doctor) and Marilyn Monroe. (TV: A Christmas Carol) Additionally, she suggests the Doctor was involved with Cleopatra whilst the Doctor suggests she had a similar connection to Stephen Fry.
 * Roundels are once again used as a means of storage. (TV: Castrovalva et al.)
 * River Song recalls the Doctor trying to bring her to Darillium. (HOMEVID: Last Night) She later mentions the actual trip to the Tenth Doctor. (TV: Forest of the Dead)
 * River Song's diary recalls previous encounters with the Doctor: "the Pandorica opens", (TV: The Pandorica Opens) a picnic at Asgard, (PROSE: Picnic at Asgard, TV: Silence in the Library) the crash of the Byzantium, (TV: Silence in the Library, Flesh and Stone), "Manhattan". (TV: The Angels Take Manhattan) Their time with "Jim the Fish" is also acknowledged. (TV: The Impossible Astronaut, GAME: The Eternity Clock)
 * River previously showed an ability to handle wiping-memory technology. (GAME: The Eternity Clock)
 * River's diary is almost full, and she is aware the Doctor would know just how many pages she needed when he gave it to her. (TV: Let's Kill Hitler)
 * The Twelfth Doctor gives River her own sonic screwdriver. This is the version seen during her investigation of the Library. He then proceeds to scan her, imprinting her image into the screwdriver so it can later be saved as a data ghost. (TV: Silence in the Library/Forest of the Dead)
 * At Darillium, River notes that the Doctor is crying. She will go on to recall this to the Tenth Doctor just before her final moments. (TV: Forest of the Dead)
 * River believes the Eleventh Doctor was the last incarnation of the Doctor because she knew his regeneration cycle was limited. (TV: The Deadly Assassin, et al.) The Doctor briefly mentions that he got past this limit. (TV: The Time of the Doctor)
 * The Doctor mentions he had a "new haircut", is in his "best suit" and is made to turn up on River's "doorstep". He is later seen in a suit at Darillium, all in line with what she tells the Tenth Doctor about the last time she saw him. (TV: Forest of the Dead)
 * The Doctor has avoided Darillium and is shown to be tearful when he finally makes good on his final date with River. The Doctor has mentioned that he does not like endings. (TV: The Angels Take Manhattan, The Name of the Doctor, The Time of the Doctor, Hell Bent)
 * The Doctor once again rewards someone with the means to gain a substantial amount of money. (TV: School Reunion, The End of Time) Interestingly, several people who have encountered the Doctor around Christmastime have now found themselves coming into large sums of money. (TV: Doctor Who, Voyage of the Damned, A Christmas Carol)
 * River pulls a fez out of her bag, an item commonly worn by the Eleventh Doctor. (TV: The Big Bang et al.)
 * Hydroflax is nicknamed "the butcher of the Bone Meadows". The Doctor and River once visited the location together. (TV: The Time of Angels)
 * River mentions the time when there were two of the Eleventh Doctor during one of the instances where the Doctor backed out of going to Darillium. The Doctor has also been promising River for ages that they would go to the Singing Towers of Darillium. (HOMEVID: First Night/Last Night)
 * The Doctor says "every Christmas is last Christmas", repeating what Clara Oswald's imagined version of Danny Pink said. (TV: Last Christmas)
 * River tries to plead the Doctor into thinking of a loophole to avoid their last outing together, but the Doctor reminds her that not everything can be avoided. There have been situations where the Doctor has been unable the change the outcome of tragic events, (TV: The Waters of Mars, Vincent and the Doctor) and he has just gone through one of these situations. (TV: Face the Raven, Heaven Sent/Hell Bent) He also reminds River that times end because they have to. (TV: The Time of the Doctor)
 * As the Doctor talks about the Singing Towers, he uses the phrase, "when the wind stands fair" to describe an instance when the towers produce a song. After being uploaded to the Library, River uses this phrase to describe an instance where "everybody lives", (TV: Forest of the Dead) something the Doctor greatly treasures. (TV: The Doctor Dances)
 * The Doctor refuses to bow to King Hydroflax, making the excuse that his back is playing up. The First Doctor was unable to bow to Kublai Khan, citing that it was because his back was broken; however, in that case, it was a valid excuse because his first incarnation was growing elderly and indeed suffering from pain trying to bend over. (TV: Marco Polo)
 * The Doctor is able to reserve a table for years in the future and arrive at the reservation in an instant. He previously pulled the same trick with Clara on Calbaron III. (COMIC: Planet of the Diners)
 * River wears a Santa-inspired coat. (COMIC: Who Who Who, Merry Christmas)
 * River owns a sonic trowel. (AUDIO: The Boundless Sea) Her paternal grandfather was a huge fan of trowels and always carried one too. (TV: Dinosaurs on a Spaceship)
 * The Doctor refers to River's sonic trowel as "just embarrassing", continuing his mocking of archaeology. (TV: Silence in the Library, The Impossible Astronaut)
 * River Song says "I hate you" to the Doctor and he replies "No, you don't", an exchange they have had before. (TV: Flesh and Stone, The Impossible Astronaut) Sounding a little more forgiving, she would go on to tell the younger Tenth Doctor "I hate you sometimes", to which he replied, "I know!" (TV: Forest of the Dead)
 * The Doctor once again finds himself wearing holographic apparel. However, this time he does not have control over it, nor wishes to actually wear it. (TV: The Time of the Doctor)
 * The Doctor, prior to changing clothes towards the end of the episode, continues to wear the replacement burgundy velvet jacket gifted to him by Clara Oswald. (TV: Hell Bent)
 * The Doctor hangs a sign on the TARDIS doors. Unlike the others, this one reads 'Carollers Will Be Criticised', not 'Out Of Order'. (PROSE: Amorality Tale, TV: The War Machines'')
 * River is implicitly aware of the Tenth Doctor's aborted regeneration, and that it counted towards the limit. (TV: Journey's End, The Time of the Doctor)

Home video releases

 * This story was released on DVD in 23 February 2016. It was also released as part of the Series 9 boxset on 7 March 2016.

Video game adaptation

 * On the 16 February 2016, a Husbands of River Song level pack was released for the game Doctor Who: Legacy. It used ten non-dialogue levels to visually retell the episode's story.