A Christmas Carol (TV story)

A Christmas Carol was the 2010 Christmas Special of Doctor Who.

It was the show's sixth Christmas special since its revival and the first Christmas special starring Matt Smith as the Doctor.

It was the first BBC Wales Christmas special neither written by Russell T Davies nor starring David Tennant. Like other Christmas specials before it, a renowned guest star was signed on to portray a major character. This special played host to the talents of actor Sir Michael Gambon, who was given two roles, portraying both the main antagonist and that character's lookalike father. A Christmas Carol was also the first Christmas story whose title was inspired by a previous Christmas tale, Charles Dickens' A Christmas Carol.

This episode contains a small hint about Amy's pregnancy. When the Doctor scans the crashing star-ship, the life signs he gets has one more than there are actual people on-board, due to it counting the baby in Amy's womb.

Furthermore, it broke the record for least delay between UK and US premiere broadcasts of an episode of Doctor Who. Previously held by The End of Time, whose US debut of Part One was a single day later, the delay between BBC One and BBC America (easternmost) broadcasts was a mere eight hours. Australia was equally well-served, with the delay being something on the order of seven hours, depending on the time zone.

Behind the scenes, it was significant for the number of new faces in most departments – more than on any other single episode since Rose. Of those new to BBC Wales Doctor Who, the most prominent were those of production designer Michael Pickwoad, costume designer Barbara Kidd, and editor Adam Recht. On the subject of a new costume designer, Matt Smith's Shetland tweed jacket ensemble made its debut in this special, replacing the outfit he wore during Series 5. It remained in use up to The Bells of Saint John: A Prequel, before Smith once again had a costume change.

Synopsis
Amy Pond and Rory Williams are trapped on a crashing space liner, and the only way the Eleventh Doctor can rescue them is to save the soul of a lonely old miser. But is Kazran Sardick, the richest man in Sardicktown, beyond redemption? And what is lurking in the fogs of Christmas Eve?

Plot
A spaceship plunges towards an unknown planet. Its captain orders the pilot to try steadying the ship. A distress call has been sent from the ship's honeymoon suite, angering the captain as she does not know who sent it. Amy and Rory, honeymooners aboard the craft, rush to the bridge of the spaceship to see if they can help; Amy is in her police woman kissogram outfit and Rory in a centurion uniform. Embarrassed, they explain they were having "fun".

Amy was the one who placed the distress call. Rory holds an odd device with a light attached and is wondering if he has to change the bulb or if the Doctor has received the signal; Amy quiets him, praying that the Doctor isn't late this time. All of a sudden, the ship's computers register a small object approaching the ship; the TARDIS soars into view, beaming the message, "Come along, Pond." When asked what the message means, Amy simply answers that it's Christmas.

Kazran Sardick, a wealthy, heartless man, owns much of the planet below — and the cloud belt above, where the ship is trapped. His money comes from a loansharking business he inherited from his father. To secure loans, he cryogenically preserves family members of borrowers for collateral. On Christmas Eve, he meets with one such family in his library. They beg for the release of a family member to spend Christmas Eve with them. Kazran rejects this proposal. He takes a phone call from the president of the planet, asking his permission to land the star-liner safely; he refuses. As he returns to berating the family, a boy notices the sound of the TARDIS landing above them.

Suddenly, the Doctor slides down the chimney into the room, calling it a whim. Babbling, he notices a "flashy-lighty thing" machine and tells the group that it's what brought him there; he tries to use the controls to open the cloud belt, but cannot use them. Kazran says the machine is isomorphic. The Doctor wonders who Kazran is, confusing the rich miser as everyone on the planet should know him; the Doctor changes the subject, wondering who the girl in the ice box is. Kazran says she is no one important, amazing the Doctor as he has never met anyone who wasn't important. He asks Kazran to help him save the ship stuck in the cloud belt, but Kazran refuses.

Kazran orders the Doctor and the family removed from his home. The servants grab the Doctor to pull him away. The family's young son throws a chunk of coal at Kazran's head. Kazran moves to strike him, but doesn't; he orders the family and the Doctor to be thrown out. The Doctor returns to ask why he didn't hit the boy. Though Kazran is less than cooperative, the Doctor quickly pieces together Kazran's personality from the arrangement of his furniture. There is a picture of his father, deceased for twenty years, but Kazran keeps his chair pointed away. Kazran fears being like his father. The Doctor says he is not because he didn't hit the boy.

Outside, the Doctor speaks to Amy over her mobile phone, but is distracted by the sight of some sky fish swimming around a lamp. The unnaturally high water level in the cloud belt, combined with the slight electrical charge, allows the fish to swim amongst the fog. A carol begins playing in the speakers in the street, preventing Amy from hearing the Doctor properly; she informs him that the ship only has an hour left. The Doctor begins panicking about what to do, babbling about what he knows about the situation; he has to turn a very mean man into a nice man on Christmas Eve. Amy asks him what the singing is in the background, but cannot hear him; the Doctor repeatedly tells her that the noise is a Christmas carol, and then suddenly gets an idea. The Doctor suddenly smiles and looks up at Kazran's mansion, and wishes Kazran a merry Christmas.

Kazran is asleep in his library, dreaming of Christmas Eve when he was only twelve years old and tried to film his encounter with a sky fish. Kazran wakes to find this video being projected onto a wall in his library; in the video, Kazran's father storms into the room and strikes his son, furious that he has disobeyed him by researching the fish. The Doctor appears behind the adult Kazran (whose entire staff has left after winning the lottery, despite there not actually being one) and wonders if he ever saw the fish; Kazran reveals that this was the day where he first began to realise that there was no one who would ever help him and that he was on his own in the world. When asked who he is, the Doctor retorts that for this night, he is the Ghost of Christmas Past.

The Doctor reveals that he can change the past and takes off as Kazran derisively declares this to be impossible. The sound of the TARDIS is heard; in the video, young Kazran looks around just as the Doctor steps into his room via the window. He gleefully jumps around, revealing that he is Kazran's new babysitter; the old one having also won the non-existent lottery. The Doctor addresses the camera, telling the future Kazran his past will now start changing; the new memories will scare him at first, but he'll get the hang of it. The adult Kazran protests that this didn't happen, but suddenly remembers that it did.

In the past, Kazran wonders who the Doctor is. The Doctor takes out his Psychic Paper to show him that he's universally recognised as a mature and responsible adult. However, it only appears as a bunch of wavy lines to the boy. The Doctor scoffs, putting the paper away; "finally a lie too big." Knowing how much Kazran wants to see a fish, the Doctor decides to help the young man make his dream come true.

Kazran and the Doctor hide in Kazran's wardrobe, luring the sky fish in through the open window with the sonic screwdriver on a string tied to the Doctor's finger. Kazran confesses to the Doctor that he is the only student in his class who has never seen a fish; he was sick at home when the cloud belt broke open and released a school-worth. Now every kid has a story except him. A moment later, the string starts moving. The Doctor opens the wardrobe door to see a small fish curiously playing with the sonic. The Doctor steps out — with the adult Kazran, remembering the event, warning him not to — and deduces how the fish survive in the fog. Suddenly, a large sky shark swoops in and gobbles up the smaller fish and half of the sonic screwdriver.

A scared Doctor backs up to the wardrobe, shutting himself inside. He tells Kazran that on the plus side, he now has a story. The shark tries getting in and rams its head into the door. Seeing its mouth stuck open, and the sonic glowing inside, the Doctor decides to give his "two tries" at getting it back. After a struggle, the Doctor manages to stun the shark, which cannot survive outside the fog belt. The Doctor tries to console a young Kazran, confessing there is nothing he can do for the shark without his sonic screwdriver, half of which is still inside the fish; though he has a means of returning it to the sky, it would never survive the trip without some form of life support. To his surprise, Kazran offers an ice box.

Kazran leads the Doctor to a large storeroom in the basement, which is filled with rows of ice boxes, all of which hold frozen people. Stopping in front of one ice box, Kazran plays its video message: its occupant is a young woman called Abigail Pettigrew, who expresses her gratitude towards Elliot Sardick and her love of the fish. Kazran explains that the people in the boxes are family members of those who have borrowed money from his father, but he insists that they can borrow Abigail's box for the night, unlocking it. Before she fully awakes, the two realise that the shark has followed them to the vault, temporarily revived by swimming in the fog that is settled on the floor.

Following a short chase, the shark is put to sleep by Abigail's singing. The Doctor explains that her voice resonates with and aligns the fog crystals in the same way that Sardick's machine does. In the present day, Kazran turns to a picture on the wall, realising that it is of Abigail. He then remembers "it's bigger on the inside". In the past, Kazran and Abigail marvel at the TARDIS. The Doctor dismisses it.

With the shark in Abigail's box, the Doctor pilots the TARDIS into the cloud belt. Dismissing his time machine as impressive, the Time Lord tells the children that he keeps the true wonders outside of the doors. He opens them, revealing the sky full of fish. They release the shark, which swims after a new meal. The Doctor notices a dial set at eight on Abigail's ice box. When he asks her if it relates to her, she responds by asking if he is one of her doctors; however, he is distracted by something else before she can explain.

The Doctor and Kazran return Abigail and her box to the vault, with Kazran promising that they will return and wake her every Christmas Eve from now on. The Doctor starts to complain as Abigail watches the door shut. However, she is next awoken by Kazran and the Doctor, wearing Santa hats. Using the sonic, he calls the shark down to pull a sleigh for them.

A third Christmas comes, with the Doctor offering to take the duo wherever in time they wish for Christmas. In the present, Kazran sees a tin-worth of pictures, showing new memories of his Christmases together with Abigail and the Doctor; he's been to New York, the Pyramids, etc. He is happy and confused by this. In the past, each Christmas has the dial on Abigail's ice box count down.

On the sixth Christmas Eve, Abigail finds Kazran much older than before and appears attracted to him. This Christmas, she requests that they visit her family; she and Kazran watch her sister, brother-in-law, and nephew prepare for the festivities through the window from outside. Abigail cries; when Kazran wonders why, she explains that it is because she is watching the life she will never be able to have. To their shock, the Doctor has gotten the family to invite them in. Abigail tells her sister of her Christmases but declines to stay the day for dinner. As a result, they have it then. The Doctor attempts a card trick, which he fails at repeatedly. Abigail's sister warns her that Kazran will turn out just like his father; however, Abigail knows there's kindness in his heart that Elliot lacks. At the end of the night, Abigail kisses a nervous Kazran.

The following Christmas finds the trio at a 20th century Hollywood party. Kazran finds a crying Abigail by the pool; when he expresses concern for her, she explains that it is time for her to tell him the truth. A few minutes later, the Doctor finds the couple kissing passionately, but impatiently requests to leave, as he has accidentally become engaged to Marilyn Monroe; he leaves with her nevertheless. Abigail sadly tells Kazran that there is nothing that can be done. When the Doctor and Kazran return Abigail to her ice box, the couple bids each other a silent and emotional goodbye. When the Doctor tells Kazran that he'll come back next year, Kazran explains that he has outgrown Christmas and would like to end their yearly ritual. With the Doctor reflecting that Kazran has not changed nearly as much as he would have liked, he offers Kazran his half of the sonic screwdriver in case Kazran ever needs him; Kazran assures him that he won't. Meanwhile, Abigail's dial has turned to one.

A few Christmas Eves later, Elliot Sardick is celebrating with his son — his machine is complete, and the planet is theirs; Elliot finally figured out part of the truth. Confused on what he should do from now on, Kazran runs to his room and takes the screwdriver out of his desk, considering using it to call the Doctor. He turns to see the Doctor standing just outside his window. Kazran goes to the window and looks on as the Doctor gives him a smile, hoping he can be of help. Angrily, Kazran shuts the curtains on him and returns the screwdriver to his desk drawer.

In the present day, Kazran goes to his old and disused room and takes the screwdriver out of the drawer and holds it, contemplating what to do. He receives another call from the president of the planet, who demands the cloud belt be opened and allow the star-liner to land safely. However, Kazran simply refuses; he explains that a very old friend (the Doctor) took many years to show him life isn't fair. Suddenly, a hologram of Amy appears in the library; she is the ghost of Christmas present. She brings him to the vault, where she has summoned dozens of holograms of the spaceship's passengers, who are singing for their lives; she explains that the Doctor was only trying to turn Kazran into a kinder man, but Kazran insists that people can't be rewritten.

He destroys the holograms and stops in front of Abigail's ice box, revealing to Amy that Abigail was mortally ill when she volunteered for the ice, and the dial showed how many days she had left to live. If he were to let her out now, he would only have one day with her. Determined, Amy projects a hologram of Kazran onto the ship's deck, where he is able to witness the chaos as the ship plunges towards the planet; the captain angrily tells Kazran that the Doctor has the ship's passengers singing with the hope that they might stabilise the ship — as Abigail was able to calm the shark — but it's not working; now, they're doing it because it gives them hope. When he is appealed to again to save the ship, Kazran angrily declares that everyone must die. Amy reveals that the Doctor has been listening, and he returns Kazran's consciousness to his body in the vault, apologising.

The Doctor says that he will now show Kazran the future, and Kazran welcomes this, knowing that he will die alone and afraid like everyone else; he repeats that he doesn't care about the people on the ship and goads the Doctor into showing him the future — only to be surprised when the Doctor explains that he already is. He points to a twelve-year-old Kazran standing in front of the TARDIS; the Doctor made Kazran the Ghost of Christmas Future. The Doctor asks the boy if he wants to turn into a heartless monster like his father. The boy mistakes his older self for his abusive father, infuriating Kazran, who goes to strike him.

However, Kazran is bombarded by his new memories of the love he and Abigail shared. Seeing his younger self cowering, Kazran realises he has to break free of his father's influence and become his own person. He hugs his trembling younger self, telling him it will be okay. Seeing he's changed Kazran into a better person, the Doctor asks him if he's ready to save the ship. With only a few minutes left, the Doctor and Kazran go to the cloud belt controls only to find that Kazran has changed too much and the machine no longer recognises him as Elliot would never let a kind person use the machine.

The elder Kazran gives the Doctor his half of the sonic screwdriver; the Doctor realises that he can transmit a signal from one half to the other — which is still contained in the shark floating in the cloud belt — but he needs it to transmit something else, something they know will work. Apologising to Kazran, he explains that they will need to release Abigail; her voice resonates perfectly with the fog crystals, and only that will calm the sky. Kazran is reluctant to let her out, but when he does so, she insists that she would have chosen Christmas Day with him for her final day.

She begins to sing her song, which unlocks the cloud belt and causes a snowfall for the first time in years. The townsfolk gather, watching in amazement at the sight of snow. Kazran watches Abigail sing, mesmerised by his beloved's beauty; she gently caresses his face. The ship's crew realises that they are able to land the ship safely, and Rory and Amy embrace. The Doctor departs with young Kazran, who now knows how his future will play out, regardless of his heartless father's actions. Old Kazran and Abigail wave goodbye; they then notice that a sleigh lies behind where the TARDIS was.

Amy and Rory meet up with the Doctor on the ground, where she notices he has built numerous snowmen along the street. The Doctor wonders why they are dressed in their costumes; Rory explains that they lost their luggage despite having a safe landing. However, the Doctor wonders why they are dressed like that at all; Amy hushes the Doctor and tries warming herself up. Rory asks if the Doctor has any more ideas for honeymoon locations. The Doctor begins babbling on about a carnivorous "moon" made of "honey" that has some "lovely views"; Rory is less than excited to hear about this idea and walks into the TARDIS.

Amy asks the Doctor if it is okay to leave things the way they are; Abigail and Kazran only have one day left together. However, the Doctor tells her that if nothing ever ended, nothing would ever get started. Rory pops out of the TARDIS, saying he answered the phone; Marilyn has called the Doctor. The Doctor tells Rory to inform Marilyn that he will call her back, "and that was never a real chapel". Amy wonders where Kazran and Abigail have gone, but the Doctor only answers "Christmas"; Amy enters the TARDIS and the Doctor follows shortly after looking up into the sky.

The scene pans above to show the snowing night sky as Kazran and Abigail fly by on their shark-drawn sleigh.

Cast

 * The Doctor - Matt Smith
 * Amy Pond - Karen Gillan
 * Rory - Arthur Darvill
 * Kazran/Elliot Sardick - Michael Gambon
 * Abigail - Katherine Jenkins
 * Young Kazran - Laurence Belcher
 * Adult Kazran - Danny Horn
 * Pilot - Leo Bill
 * Captain - Pooky Quesnel
 * Co-pilot - Micah Balfour
 * Old Benjamin - Steve North
 * Boy & Benjamin - Bailey Pepper
 * Servant - Tim Plester
 * Eric - Nick Malinowski
 * Isabella - Laura Rogers
 * Old Isabella - Meg Wynn-Owen

The Doctor

 * The Doctor admits he thinks bow ties are cool because '[he wears them] and [doesn't] care'.

Culture

 * Abigail's song mentions "Silence" several times.
 * The song Abigail sings to calm the shark is "In the Bleak Midwinter", a Christmas carol based on a poem by English poet Christina Rossetti.
 * The Doctor wonders if Kazran has seen Mary Poppins.
 * The Doctor hears the song "Ding Dong Merrily on High" playing.
 * The passengers of the ship are singing "Silent Night".

Individuals

 * Mrs Mantovani was Kazran's nanny.

Locations

 * The Doctor, Kazran and Abigail appear to have visited (according to Kazran's photos): the Pyramids and the Sphinx in Egypt; the Sydney Opera House and Uluru in Australia; the Eiffel Tower in France; and the Statue of Liberty, the Empire State Building, and California in 1952, specifically Hollywood in the United States of America.
 * Elliot Sardick has a Cryo-Cave below his house.

Species

 * The Doctor mentions face spiders.

Story notes

 * A Christmas Carol is loosely based on the Charles Dickens novel of the same name, with Kazran Sardick being Ebenezer Scrooge, the Doctor being the Ghost of Christmas Past, Amy being the Ghost of Christmas Present and Kazran himself being the Ghost of Christmas Yet to Come.
 * The first footage from this special was screened on 19 November in the form of a trailer as part of the BBC's Children in Need.
 * Arthur Darvill is promoted to the main cast from this episode onwards with his name appearing in the opening titles.
 * Steven Moffat said before it aired that this episode would be the most "Christmassy Christmas special ever," adding, "It's all your favourite Christmas movies at once, in an hour, with monsters and the Doctor and a honeymoon..."
 * This is the first Christmas special since The Christmas Invasion to feature the Doctor's regular companions. This is also the first Christmas special not to be set primarily on or near Earth.
 * Paul Cornell's short story The Hopes and Fears of All the Years likewise features the Doctor visiting an individual every year at Christmas time, though in that case on Christmas Day, not Christmas Eve by virtue of time travel. Both stories also involve the Doctor arriving on the scene by coming down the chimney.
 * This is the first Christmas special not to feature David Tennant and the first one not to be written by Russell T Davies. It is the first one to feature Matt Smith and first to be written by Steven Moffat.
 * The shark, despite being a female, was named "Clive" behind the scenes. Matt Smith and Laurence Belcher also claimed to have called it "Percy" and "Clyde".
 * Excluding the little fish eaten by the shark, this is the first Christmas special without a character's death.
 * Since Amy was replaced with a Ganger in the following season, this is presumably the last episode to feature the actual Amy Pond until the end of The Almost People.
 * "Abigail's Song" is the first English-language song to be composed for Doctor Who since "The Stowaway" and is the first original song to actually play a direct role in resolving the plot.
 * Michael Gambon is well known for taking over the role of Albus Dumbledore in Harry Potter and the Prisoner of Azkaban, coincidentally the only Harry Potter film that includes time travel.
 * The Doctor travelling back in time to make someone react more favourably to him was part of the plot of the Decalog 3: Consequences short story Continuity Errors, also written by Moffat.
 * Andy Pryor, the casting director, did not believe that Michael Gambon would be available, and was surprised when Gambon accepted the role. Matt Smith, Karen Gillan, and Arthur Darvill were very honoured to work with him.
 * This episode was Katherine Jenkins' acting début. She got the news that she'd been cast on her thirtieth birthday.
 * Michael Gambon is only the second knighted actor to appear in the series. The first was Sir Derek Jacobi, the third was Sir Ian McKellen and the fourth was Sir John Hurt.
 * Steven Moffat wrote the script in Los Angeles, as he, Matt Smith, Karen Gillan and others were stranded there while on a promotional junket thanks to the eruption of the Iceland volcano Eyjafjallajökull. Moffat set to work on scripting the Christmas special despite his decidedly non-wintry surroundings, eventually downloading a playlist of seasonal tunes to help him overcome writer's block.
 * Danny Horn admitted to actually being nervous about his on-screen kiss with Katherine Jenkins, largely because her boyfriend at the time was somewhat intimidating and happened to be on set that day.
 * The painting of Kazran's father was created by taking a picture of Michael Gambon, lightly printing it on a canvas, and painting in the details.
 * Kazran's controls were inspired by a church organ.
 * Nearly all the windows in the town are round, reminiscent of submarines.
 * For the scene in which a sky fish nibbles on the sonic screwdriver, the screwdriver was dangled in front of a greenscreen and tapped with a pen to create the effect of the fish nudging it.
 * The flying shark was inspired by Steven Moffat's childhood fear of sharks rising out of water.
 * The Doctor produces a picture of himself with Albert Einstein towards the beginning of the special. Matt Smith wrote fan fiction about the Doctor meeting Einstein after being cast to prepare himself for the role.
 * Matt Smith named this as his favourite Christmas Special.

Ratings

 * 10.3 million (Overnight)
 * 12.11 million (BARB)

Rumours

 * The villain has been confirmed by the BBC to be a CGI "Flying Shark". Although the main enemy was Kazran Sardick, there was a menacing, flying shark.
 * The episode could be a musical . This was false, although Katherine Jenkins did sing.
 * The episode will be set on a planet that looks Victorian and will have flying sharks. This was true.
 * In the episode, the Eleventh Doctor will get engaged. He was accidentally engaged to Marilyn Monroe, and this leads up to a gag at the end of the episode.
 * The Doctor will pose as a Ghost of Christmas Past. In a trailer for the BBC's Christmas season, the Doctor is heard saying "I'm a ghost of Christmas Past". This was true, with the Doctor travelling back in time to Kazran's past, and from there, affect his future.

Filming locations
to be added

Production errors

 * When the Doctor first goes back to Kazran's childhood, the light from the TARDIS windows can be seen through the crack in the door after the supposed departure. Additionally, though the TARDIS can be seen in the background at the beginning of this scene, it is absent in the exterior shot where the Doctor is standing in the window.
 * When the Doctor hurriedly tells Kazran and Abigail they have to leave the party in 1952, the boom mic can briefly be seen in the shot.

Continuity

 * Amy says, "Don't be late, Doctor, just this once." (TV: The Eleventh Hour)
 * The Doctor sends a message to Amy saying, "Come Along Pond." (TV: Victory of the Daleks, The Big Bang)
 * The Doctor attempts and fails to perform card tricks. (TV: Robot, Rose)
 * The Doctor produces a photograph of himself and Father Christmas with Albert Einstein at Frank Sinatra's hunting lodge. It was previously suggested that the Doctor and Einstein were friends. (TV: Time and the Rani) This is later proven when the Doctor and Einstein are together on the TARDIS. (TV: Death Is the Only Answer)
 * While in the honeymoon suite, Amy wears her policewoman kissogram garb, (TV: The Eleventh Hour) and Rory wears a Roman Centurion's outfit, just like the one worn by his Auton self, and previously by his real self (as seen in a photograph in Amy's house), or this was the Christmas event that the photograph was of. (TV: The Pandorica Opens)
 * Once again, the Doctor replaces somebody who unexpectedly wins the lottery, despite the fact that that person would not normally play it. (TV: School Reunion)
 * The Doctor once again wears a fez, (TV: The Big Bang) but this time he's actually going to Egypt.
 * During one of his visits to Abigail, the Doctor and Kazran wear long scarves similar to the one worn by the Doctor's fourth incarnation. (TV: Robot, et al.) During this Christmas, Abigail's timer shows "004."
 * The Doctor has previously observed and attempted to use devices with isomorphic controls to no avail, a notable example being the Master's laser screwdriver. (TV: Last of the Time Lords) The Doctor has also previously stated (apparently falsely) that the TARDIS has isomorphic controls. (TV: Pyramids of Mars)
 * Abigail says she cannot enter her home, before seconds later seeing the Doctor within - closely resembling the Doctor telling Amy not to interfere before she sees him on the TARDIS monitor doing so. (TV: The Beast Below)
 * The Captain claims that "Christmas is cancelled!" (TV: The End of Time)
 * The Doctor once again says, "Geronimo!" (TV: The End of Time, The Beast Below, The Big Bang)
 * The Doctor gets himself into a problematic marital situation with Marilyn Monroe. He previously had a failed marriage with Queen Elizabeth I (TV: The Shakespeare Code, The End of Time) and he has stated that he is "rubbish at weddings... especially my own." (TV: Blink)
 * The Doctor, when speaking to Kazran, said, "900 years of time and space, I've never met anyone who wasn't important". He said something along the same lines to Craig Owens when Craig was sick. (TV: The Lodger) This is also similar to his lines while talking to another bride and groom (TV: Father's Day) and later while examining stone dust. (TV: The Day of the Doctor)
 * The Doctor previously mentioned having seen fish that fly. (TV: Marco Polo)
 * The Doctor gives Sardick a choice: help those people on the starliner or face the consequences. When he refuses the Doctor says, "Whatever happens here tonight, remember: You brought this on yourself." The Tenth Doctor told the Empress of the Racnoss much the same thing when he offered her a choice to either leave or face the consequences. (TV: The Runaway Bride)
 * The psychic paper has failed before. (TV: Army of Ghosts, The Shakespeare Code, The Vampires of Venice)
 * This episode marks the fifth time the Doctor's sonic screwdriver has been destroyed. (TV: The Visitation, Smith and Jones, The Eleventh Hour, COMIC: The Flood) The device would later suffer heavy damage for a sixth time. (TV: Oxygen)
 * The Byzantium was also identified as a Galaxy Class ship. (TV: The Time of Angels)
 * At the party where he ended up engaged to Marilyn Monroe, he met up with John F. Kennedy. (PROSE: Shroud of Sorrow)
 * The Eleventh Doctor claimed to accidentally become engaged to Marilyn Monroe. The First Doctor also accidentally became engaged, to Cameca. (TV: The Aztecs)
 * During his travels with the Doctor as a young man, Kazran met Winston Churchill and the two of them became stranded in Britain in 55 BC during Julius Caesar's invasion. (AUDIO: Living History)
 * During his seventh incarnation, the Doctor previously sang another duet with Sinatra, though much less successfully on that occasion. Melanie Bush noted that the two of them and Ace were lucky to escape with their lives since Sinatra was less accommodating than the Doctor had hoped. (AUDIO: Maker of Demons)

DVD & Blu-Ray releases

 * This story was released on DVD and Blu-ray on 24 January 2011 in UK markets and 15 February 2011 in North American markets.
 * The episode was later released in the complete series 6, which included the first and second half of the series, was released on DVD and Blu-ray on the 21 November 2011.
 * A Christmas Carol was released on Region 2 DVD, and Region B Blu-ray on 20 January 2014 as part of The Time of the Doctor + Other Eleventh Doctor Christmas Specials set. The Doctor, the Widow and the Wardrobe, The Snowmen and The Time of the Doctor were also included on both versions.

Digital releases

 * A bundle including the Christmas Specials mentioned above was released on Google Play, iTunes and Amazon Instant Video in HD or SD. It included the Farewell to Matt Smith featurette. The Amazon Instant Video release also added Prequel to the Doctor, the Widow and the Wardrobe, Vastra Investigates and The Great Detective.
 * The story was missing from Netflix until 2014 when it was added as episode 14 of Series 5, in contrast with previous Christmas specials which are considered episode 1 of the following series (for example, The Christmas Invasion is considered the beginning of Series 2). It is also available on Hulu and iTunes.