Planet of the Dead (TV story)

Planet of the Dead was the first of the specials that aired throughout 2009. It was also notable as being the first Doctor Who Easter special.

Planet of the Dead also featured guest star Michelle Ryan as Lady Christina de Souza, who acted as the companion for the episode, continuing the practice of pairing a guest actor with the Doctor during a special.

Planet of the Dead was also notable for introducing the "he will knock four times" and "something is returning" arcs, something that would come up again in the following story, The Waters of Mars and ultimately conclude in the two-part serial The End of Time.

From a production point of view, Planet of the Dead was the first episode of the revived series of Doctor Who to be written by two people, Russell T Davies and Gareth Roberts.

The most notable point about Planet of the Dead was that it was the two-hundredth Doctor Who story, and as such, the bus featured in the episode was named the 200 to connote the celebration.

At roughly the same time as the premiere of the 200th story, Doctor Who Magazine featured a list of the most-favourite stories as voted by the fans since the first adventure, An Unearthly Child, was broadcast. Planet of the Dead clocked in at #99.

Planet of the Dead was also the first episode to be filmed and broadcast in high-definition. From this episode onward, the series would remain in HD format.

Synopsis
When a London bus takes a detour to an alien world, the Tenth Doctor must join forces with the extraordinary Lady Christina. But the mysterious planet holds terrifying secrets and time is running out as the deadly Swarm gets closer...

Plot
As the night shift of the International Gallery museum commences, armed guards are at work protecting a highly-coveted golden goblet. One guard types out a security code to unlock a security system level. He turns to the side, raising a four-sided barricade of laser alarm sensors around the cup. It might seem foolproof, but the one thing the guards haven't counted on is a sleuth attempt to pilfer the cup from above...

While their backs are turned, a round panel is quietly pried loose from the domed ceiling of the museum. On the rooftop is a woman in a black clothes and a ski mask. She peers down and assesses the security detail. The woman lowers herself from the roof, flawlessly infiltrates the museum without setting off the alarms, and replaces the cup with a mechanical Maneki Neko; when the guards finally turn around at the sound of her releasing her winch on the roof, she waves at them in a mocking fashion. As the alarms go off, she dashes out of the museum and unmasks; she is Lady Christina de Souza, an expert thief. Christina runs out to the street to see someone being arrested, and she says, "Sorry, lover" to her presumed accomplice, getting away with the prize while he takes the fall.

She then takes a back route onto the main road, where she frantically looks for a way out as police move in searching for her, although unaware of her presence. She runs onto a 200 bus to Victoria, where she exchanges her diamond earrings for a bus ride. Soon afterwards, the Tenth Doctor comes onto the bus, and uses a psychic paper on the Oyster card scanner. He then sits down opposite Lady Christina.

After enjoying a chocolate Easter egg and engaging in some small talk with Christina, he receives an alert from the rhondium sensor in his pocket that the particles he's been looking for have been detected. As he fiddles with the sensor, he gets inquisitive looks from a young man sitting parallel to him.

The police are still after Christina, since they know she has stolen the cup. Christina is visibly frightened by the sound of the wailing sirens, giving the Doctor reason to wonder if she's hiding something. It looks like the vehicle is about to be pulled over, but whilst chasing the bus through a tunnel, the police witness it disappear in front of their eyes; startled, they set up a perimeter around the area. Meanwhile, the bus passes through a ripple in space and a bright, blinding light flashes out. The passengers scream as the bus is put through the wringer; the metal frame buckles, causing ts windows burst into shards of flying glass, and everyone ducks down in their rows. After the bus takes a hard landing back onto solid ground, the Doctor's jaw is agape at the sight of a completely different environment. Rather than tarmac, street lamps, and dark, rainy nighttime skies, it is now daytime, with sand as far the eye can see in every direction. They have been spat out into a world covered in desert with three suns. The bus has been wrecked in the process of landing, with smoke hissing from its engine and parts of its double-decker roof sheared apart. The bus driver proclaims it unmovable. The Doctor tells the passengers that the bus has passed through a wormhole into a different world, proving this to them by throwing a handful of sand into the space behind the bus. The sand causes a rippling effect in the air. The same man who eyeballed the rhondium detector points a finger at the Doctor and demands to know if he used it to make the bus end up in the desert. Annoyed for receiving immediate blame from a human on a bus and having dealt with the animosity of the Midnight incident, the Doctor doesn't keep to himself again. Instead, he comes clean and says he was tracking a hole in reality that suddenly grew big and the bus drove into it. He elaborates that the other end of the wormhole was in the tunnel on Earth. Among the passengers is Carmen, who has been hearing mysterious voices since Christina got on. The bus driver announces his desire to return to Earth, and promptly runs through the wormhole, accompanied by the Doctor's, "No, don't!". The other passengers of the bus witness the driver's skin and tissues incinerating, before he disappears into the wormhole with the same rippling effect as the sand.

Meanwhile on Earth, where the police are watching the wormhole, the driver's blackened skeleton steps out, halts, and then tumbles to the ground. Unnerved, the police declare an emergency Code One, calling UNIT to the scene. Captain Erisa Magambo commands the operation and she tells her soldiers to fire at anything that comes through the wormhole.

After watching the bus driver's death, the Doctor sums up that the metal of the bus protected them from the same fate as the driver when they passed through the wormhole (like a, as Christina states). Everyone returns to the bus so the group can make sense of the situation. Christina takes charge, introduces herself and the Doctor, then everyone introduces themselves: Nathan, a young adult with slicked up hair, Barclay, about the same age and the one who confronted the Doctor, Angela Whittaker, an older blond woman, Louis, who goes by the nickname "Lou," and his wife, Carmen. Christina notices the Doctor is the brainpower of the bunch and has him fill the rest of the group in on what has happened.

The Doctor explains to the passengers of the bus that they went through the wormhole by accident, but Carmen tells him with surprising knowledge that it was a doorway put there for a reason. Her husband Lou notes she has had a gift of foresight since she was a girl which has helped them make small wins on the lottery. The Doctor deems Carmen a low-level psychic, and theorises the alien sun has amplified her abilities. He asks her if she can see anything. She foretells, "Something is coming, riding on the wind and shining." When asked what she means, she answers, "Death. Death is coming."

Her words send Angela into complete hysterics, Nathan panics no one will find them, Barclay begins to get rebellious, and both Christina and Lou are drowned out by the uproar. The Doctor quells the clamouring bus and regains control, but Angela is still sobbing heavily. He instinctively grips her by the arms to get her attention and asks where she was heading to take her mind off the peril. She replies she was going home to her family, Mike and Suzanne; thinking about them calms her and abolishes her panicky state. The Doctor moves on to Barclay, who has a love interest named Tina; Nathan's dealing with unemployment; and Carmen and Lou talk about whose turn it is to cook. The Doctor asks Christina where she was going; she is the only person in the bus with something to hide. She tells him she was going far away, not giving away her thievery. Having defused the tension in the bus, the Doctor reminds the group to focus on those pleasant thoughts so the fear doesn't set in again, then informs them the planet outside is "nothing compared to all those things waiting for you" on Earth. He promises to get them all home.

Back on Earth, the highway tunnel has been shut down as Detective Macmillan and the police officers wait to intercept Lady Christina. They find themselves joined by a fleet of UNIT soldiers and weapon-toting armoured vehicles, and have to deal with the troops forcibly interfering with their line of work. Captain Magambo establishes a strategic hold on the highway. The detective tries to remain in control, but a soldier holds him back as a firing squad readies themselves to open fire if anything hostile emerges through the wormhole.

Nathan and Barclay dismantle part of the bus's upholstered seats and bring them to the Doctor, who wants to wedge them beneath the wheels of the bus like duckboards. This will give the wheels enough traction to throw the bus in reverse and back through the wormhole. Using experience from trips to the Kalahari, Christina has them air out the tyres slightly to improve it further by giving the bus extra grip, as its weight is more distributed. When Barclay is distressed over how deep the wheels will run, Christina produces a fold-up spade from her rucksack to begin digging them out, then a small axe for Nathan to unearth the seats more quickly. This piques the Doctor's curiosity, but he is distracted when Angela asks for a key to get the bus running. The Doctor informs her the bus doesn't use keys, just a master switch and stop and go buttons. She follows his instructions and attempts to start the bus. The engine cranks and coughs, but fails to get going. Christina and the Doctor pop open the 200's hood to find it gummed up with sand. Christina asks if anyone has experience with mechanics, and Barclay states he does. He is assigned the task of stripping the air filter. The Doctor wanders off, causing Christina to chase after him. Unbeknownst to them, they are being watched from a monitor by a creature with insectoid hands.

The Doctor questions Christina about her toting a backpack that she refuses to let out of her sight, which has an axe and spade inside by happenstance. That along with her fear of sirens has him wondering what she's running from. She initially refuses to answer his questions, instead calling herself and the Doctor "two equal mysteries." After a bit more conversation, however, Lady Christina de Souza announces her full title to him, and they shake hands. In response to her claim of nobility, the Doctor says he is a Lord of a "big estate". Growing savvy, Christina notices the Doctor seems unusually acclimated to the out of the ordinary. He pulls her attention off the subject and exclaims, "Allons-y!" Christina impresses him with some articulate knowledge of the French language herself; "Oui mais pas si nous allons vers un cauchemar." As they continue walking in the desert, they see what appears to be storm clouds approaching. Christina fears it could be a deadly sandstorm, but the Doctor thinks it is something worse. "It's a storm — who says it's sand?" he notes mysteriously.

The Doctor and Christina rush back to the bus as Carmen begins to have distressing visions. He borrows Barclay's cell phone, pulling out his sonic screwdriver and turning it into a superphone. The Doctor then attempts to call someone on Earth. Unsure of the number, he dials Pizza Geronimo by accident. Redialling the correct number, he's connected to UNIT's automated phone system. Angela gives him a tip to hold "0"; it overrides the machine, which allows one to speak with a real person. Through the helpline, the Doctor gets in touch with UNIT at the tunnel. Speaking to Captain Magambo, the Doctor informs her of the crisis, tells her he is stranded without his TARDIS. Magambo connects him with UNIT's scientific advisor, Malcolm Taylor, who is beyond elated to know he's speaking to the one person he's always wanted to meet. Malcolm describes an ingenious process of measuring the wormhole by creating a reflection of its energy readings, which prompts the Doctor to request a capacity scan so he can get a full idea of what the wormhole is like. He deems Malcolm his "new best friend" and hangs up for the time being.

The group sets back to digging the bus wheels out from the sand in order to enable them to move it back through the wormhole. The Doctor and Christina set off to explore the area. They find that the storm from earlier has grown closer. The Doctor takes a snapshot of the storm on Barclay's phone to send to Malcolm for further analysis. From what he and Christina can tell, it looks like a massive sandstorm sweeping across the planet towards them, glinting in the sun as if made from metal. On the bus, Carmen shudders as her visions tell her these things are a storm that devours. At the same time on the dunes, the Doctor and Christina are found and captured by a fly-like alien who holds them at gunpoint with a blaster.

The Doctor and Christina are escorted to the alien's crashed ship, where another alien is waiting. One points a blaster at them and blames the Doctor for their crashed ship. The Doctor soon explains to the two aliens, who identify themselves as Tritovores, that they mean them no harm. He assures them that "the 200", which is how the aliens refer to the bus due to its route number, is trapped on the planet just as they are. The Tritovores in turn become more friendly; the telepathic translation devices they use enable them to know the Doctor is not lying. The Doctor then asks them to send a probe out to investigate the sandstorm seen earlier. When told that the ship is without power, he promptly fixes the ship's power to launch it with a well-placed kick. He and Christina learn they are in the Scorpion Nebula on the planet San Helios. The aliens explain that they had been on their way to trade with the people of San Helios when their ship had crashed. They show a hologram depicting San Helios as a thriving environment with advanced cities. Christina notices the Doctor treats the visual of the amazing city like he's used to such things, then asks about his title of lordship. He reveals he comes from a race of Time Lords. Christina suggests they should seek out the city in San Helios for help; the Doctor isn't so sure it will be that simple. The Tritovores give the Doctor information that the entire planet became a desert last year, with all 100 billion inhabitants suddenly vanishing along with the city, wildlife, oceans, and mountains. Everything has been reduced to sand, including the inhabitants. The idea of having "dead people" in her hair repulses Christina, whose hair has sand caught in it. She quickly attempts to stroke it out.

The Doctor receives a phone call from Malcolm and Magambo. The wormhole has grown to four miles in length and is heading outward. Neither Malcolm nor the Doctor can understand what could make it grow on its own. Magambo has ordered all aircraft above London grounded to keep others from falling in. She wants him to answer if the wormhole could be dangerous to the planet, but Barclay's phone picks up a call waiting. The Doctor cuts off his conversation, knowing the answer would cause more trouble.

Switching over to the second caller, the Doctor picks up Nathan on the other end, using another mobile phone. Their attempts to get the bus dislodged from the sand have exhausted all the petrol, putting them back at square one, and Nathan wonders if the Doctor can hold true to his promise in spite of the marooned bus. The Doctor does not answer. He leaves the call hanging at the sound of beeping from the Tritovore ship's controls. The probe has reached the storm.

The camera on the probe is transmitting unsettling footage. It shows that the "storm" is a swarm of billions of carnivorous stingray-like aliens with metal exoskeletons before the transmission is cut off by the probe being eaten by one of the alien stingrays. The Doctor then analyses the alien physique by the data they get and theorises that they must be creating the wormhole effect. Their velocity as a pack is reaching a speed that creates static buildup with enough energy to pierce open the fabric of space. When asked why they don't burn up upon passing through, the Doctor replies that any metal they eat gets extruded into their bones. It has made them immune to the effects of the wormhole because their exoskeletons have transformed into metal. They've been using the portals to jump through space and prey on anything they find edible. Another, scarier realisation dawns on him — all of San Helios has been devoured by these predators. What remains of it, including the dead, makes up the sand of the deserts.

The Tritovores and the Doctor plan to get away from the planet before the swarm hits their area, and need to get the crystal power source that makes the Tritovorian ship fly. The Doctor and the two aliens try to bring up the source manually, but the entire system is unresponsive, lacking power. Christina, in the meantime, prepares her cat burgling equipment, and lines down the shaft with her winch. The Doctor stops her just in time before she is electrocuted by a security grid. After disabling it, she makes her way slowly down the shaft. While curiously flipping the top of her rucksack, the Doctor tells Christina about himself. He talks about how he can travel through time and space in his blue box and some of the places he's been, including the Court of King Athelstan in 924 AD... but he didn't remember her being there. At this, he pulls the Cup of Athelstan out of her bag.

He realises that she's a thief, and she says she prefers to say she "liberated" it. The Doctor doesn't approve of her lifestyle of thievery, but levels with her, admitting he stole the TARDIS from his own people. While Christina lowers down the gravity well, a screech rings out from below. The Doctor remembers they never found out why the Tritovores crashed, until he's informed they have an open-vent system. Much like birds being sucked into an airplane, he suspects a stingray got pulled into the ship. As he feared, when Christina reaches the bottom of the shaft to get the crystal and its holding brackets, she sees a sleeping stingray behind some metal poles; it quickly stirs from its resting place. The Doctor tells her that it had been dormant from the cold, but the temperature is being raised by her body heat and is waking it up. She replies she has that effect on men, but the Doctor isn't laughing; he urges her to hurry and, once she has the fixture in hand, brings her back up. The alien stingray which was down in the shaft next to Christina gives chase, but it gets fried in the security grid after she turns it back on whilst ascending. As they run away with the Tritovores out of the ship, the Doctor offers them a means of escape on the 200. Before they accept, a deafening roar booms through the ship. The Doctor wonders if the Tritovores collided with more than one stingray, and speculates that it could be munching through the metal sleeve-covered infrastructure of the ship. One of the Tritovores gets ready to escape the ship, but the other goes back to shut down the controls. Another stingray bursts in from above and knocks him over, then gulps him down its jaws. The other, in rage, prepares to fire its weapon at the Stingray, but before he can, he is eaten as well.

The Doctor and Christina run to the bus. Once there, the Doctor pitches the crystal into the sand because he doesn't need it since it only worked to power the alien ship's components, not an Earth-built bus. Christina protests she risked her life for it, but the Doctor corrects her: she risked her life for the clamps it was mounted on. The Doctor attaches 4 Tritovorian anti-gravity clamps onto the wheels, and uses the 5th to interface the bus steering wheel with the Tritovorian technology. The Doctor calls Malcolm, telling him that they need to prepare to close the wormhole. Malcolm figures out a way to do it and starts on the process immediately.

Integrating the 5th anti-gravity clamp to the bus's steering proves difficult, as the two technologies are incompatible alone; he needs something soft, malleable, non-corrosive and able to conduct electricity, suggesting gold, to act as an interface. Reluctantly, Christina hands the Doctor the Cup of Athelstan along with a hammer upon request. She asks him to "be careful with it" as it is a millennia-old artifact worth 18 million pounds. He promises to do so, then smashes it to bits so it fits between the bus wheel and the anti-gravity clamp controller. In response, Christina says, "I hate you".

Once Malcolm is ready to close the wormhole, Captain Magambo orders him to close it to protect the Earth, despite the fact the Doctor and the passengers of Bus 200 are still trapped on the other side. Morally outraged at the idea of abandoning the Doctor who has saved humanity countless times before, Malcolm refuses to follow her order so they can allow the Doctor to get back to Earth. Drawing her gun on him, Magambo once again orders him to close the wormhole in the hopes of intimidating him. In spite of his fear, Malcolm passionately refuses to close the wormhole, surprising even Magambo.

Their argument buys the Doctor precious time. He is able to make the bus lift out of the sand and into the air, flying back through the wormhole to Earth. However, the swarm is hard upon its heels. The tense stand-off between Captain Magambo and Malcolm is defused when a soldier tells her the bus is safely through, but they are not out of danger. Three of the stingrays have followed the bus through the wormhole; furthermore, if they don't close the wormhole in time, the entire swarm will come through and devastate Earth.

As the Doctor flies the bus across London, he attempts to dodge the stingrays whilst helping Malcolm overcome some technological difficulties via mobile phone. With just seconds to spare, Malcolm is able to close the wormhole just ahead of the main swarm while UNIT soldiers kill two of the stingrays in a small battle. The Doctor is able to send the third stingray to its death with some fancy evasive manoeuvres in the sky, knocking it away. After he manages this, Christina passionately kisses the Doctor, taking back her earlier comment of "hating him".

The bus lands back on the spot where it vanished, and the passengers are released and taken to be examined by UNIT. The Doctor meets Malcolm, who embraces him in a hug and exclaims, "I love you!" four times, to the Doctor's bemusement. Magambo gives the Doctor a salute even though he doesn't want one, trusting him that the creatures will not return. The Doctor replies they will generate more doorways; it is part of their natural life cycle and something they can't help, but he'll try to nudge them onto uninhabited worlds. He also puts in a good word for Nathan, who needs a new job, and Barclay, who is good with engines, saying they're good to have in a crisis if Magambo would bring them on to UNIT as privates. Magambo then informs the Doctor that they found the TARDIS at Buckingham Palace, revealing it in the back of a military truck. They part on friendly terms.

Christina, meanwhile, is being searched by UNIT soldiers, but she breaks off and runs to the Doctor. D.I Macmillan immediately moves in to capture her at last, but Christina hopes the Doctor will help her escape in the TARDIS. Additionally, she wants to come with him for adventure and excitement, telling him that is why she steals. Despite the fact that he had earlier proclaimed them to be "the perfect team", he says no. When she asks him why, he replies sadly, "People have travelled with me, and I've lost them. Lost them all. Never again." He looks on silently as D.I Macmillan proudly arrives to confront Christina with the charge of suspicion of theft. The police promptly arrest her and take her away, leaving the unperturbed Doctor by himself.

The Doctor, about to enter the TARDIS, is told by Carmen to take care of himself; the Doctor, full of joy, tells her the same. However, she replies, "No, but you be careful, because your song is ending, sir!" When the bemused Doctor asks what she means by this, Carmen replies, "It is returning. It is returning through the dark, and then Doctor...oh but then... he will knock four times." The implication of this prophecy leaves the Doctor very unnerved.

After Carmen leaves, the Doctor decides to take pity on Christina, who is now handcuffed and being put in a police car. The Doctor points his sonic screwdriver at her handcuffs and frees her hands. Christina gets in the police car on one side and gets out on the other. She heads for the bus, chased by the police, and closes the doors after she gets on it. Macmillan furiously orders her to open them, but the Doctor advises him to step back. The inspector charges him with aiding and abetting; the Doctor feigns remorse and heads over to the TARDIS, saying, "I'll just step inside this police box and arrest myself." The bus takes off, flying over the inspector's head and hovering over the TARDIS; the door opens as the others watch. Smiling down at the Doctor, Christina happily tells him, "We could have been so good together", revealing no hard feelings over her rejection. The Doctor merely smiles back and replies, "Christina, we were." Christina flies off into the night, the other passengers cheering her off, and the Doctor merely watching; the Doctor then heads into the TARDIS.

Cast

 * The Doctor - David Tennant
 * Lady Christina de Souza - Michelle Ryan
 * Professor Malcolm Taylor - Lee Evans
 * Captain Erisa Magambo - Noma Dumezweni
 * D.I Macmillan - Adam James
 * Lou - Reginald Tsiboe
 * Carmen - Ellen Thomas
 * Angela - Victoria Alcock
 * Barclay - Daniel Kaluuya
 * Nathan - David Ames
 * Bus Driver - Keith Perry
 * Sgt Dennison - Glenn Doherty
 * Sgt Ian Jenner - James Layton
 * Sorvin - Paul Kasey
 * Praygat - Ruari Mears

Uncredited

 * June Campbell Davies - Traffic Controller

Christina de Souza

 * Christina compares the bus to a Faraday cage.
 * Christina mirrors past companion Ace by carrying around a backpack full of various tools.
 * Christina kisses the Doctor just like several other female companions have done before.

Astronomical objects

 * The bus is transported to the Scorpion Nebula on the other side of the universe.
 * The sun on San Helios is intense enough to warrant the use of sunglasses.
 * San Helios was once a populated world, but became a desert over the course of a year or less, with all evidence of civilisation devoured from its surface. The sand is all that remains.
 * Barclay and Nathan mention the stolen planets.

The Doctor

 * The Doctor's sonic screwdriver can be used to tint the lens of his glasses and even the frames to effectively make them look like sunglasses.
 * Carmen makes a prediction for the Doctor's future using her psychic gift: "Your song is ending, sir. It is returning. It is returning through the dark. And then, Doctor, he will knock four times." This prophecy reflects the Ood's message to the Doctor, "Your song will end soon". It's later revealed that the "it" that's returning is Gallifrey and "he" is Wilfred Mott, trying to get the Doctor's attention to release him from a containment chamber after the Doctor and the Master defeat Rassilon. This does lead to the Doctor's death as he absorbs a fatal dose of radiation to rescue Wilfred, which forces him to regenerate.
 * The Doctor said that he will "never" take another companion on board the TARDIS because he has lost all his previous ones.
 * The Doctor's psychic paper is compatible with the Oyster card scheme used for public transport in London and he uses his psychic paper to 'pay' his bus fare.
 * The Doctor admits that he stole his TARDIS from his own people.

Foods and beverages

 * The Doctor offers Christina the rest of his chocolate Easter egg because he's determined to keep his teeth.
 * Carmen and Lou were going to have tea with a side of chops and gravy at their home.
 * The Doctor mis-dials UNIT's phone number and calls Pizza Geronimo by mistake.

Physics

 * The Doctor's device is attempting to detect rhondium particles.
 * A wavelength parcel of ten kilohertz operating in four dimensions equals one Malcolm. 100 Malcolms are equal to 1 Bernard.

United Nations Intelligence Taskforce

 * UNIT is called in by the police to assist in locating the bus.
 * UNIT has an automated phone system. Like most standard phone systems, however, pressing zero bypasses the automation and connects with an operator. UNIT's phone number contains the numbers 7-6. Reversing those numbers calls up a pizzeria instead.
 * UNIT troops are equipped with H&amp;K G36 assault rifles, M4 carbines, and Walther P99 pistols.
 * Malcolm's apparel as he leaves his laboratory is similar to that of the Doctor's fourth incarnation.
 * UNIT maintains extensive files about the Doctor.

Real world

 * Oyster cards, a form of electronic payment on London buses, are referenced, with Christina making a joke about them in an unsuccessful attempt to board the bus without paying. The Doctor uses his psychic paper in lieu of one.
 * Angela learned that holding the "0" button on a phone will cut off an automated phone system and patch the caller in to a real person from the investigative journalism UK TV series Watchdog.

Story notes

 * Planet of the Dead started at the second half of the of ITV's rival Saturday night drama, , . As such, this is the first time a Doctor Who television story has been shown at the same time as an episode of Primeval, which at the time of its premiere was described as ITV's answer to Doctor Who.
 * The Number 200 story strand comes from the New Adventures novel The Highest Science written by Planet of the Dead co-writer Gareth Roberts. As this episode is the 200th storyline of Doctor Who, the episode makes an in-universe reference to this by calling the bus the 200. DWM 407 confirmed that Planet of the Dead was Doctor Who's 200th story.
 * Planet of the Dead had a one-off companion, Lady Christina de Souza, who was unique amongst her BBC Wales predecessors in that she was depicted as both a criminal and a member of the British aristocracy. The episode also featured the return of UNIT for its third story in 12 months. Narratively, it was perhaps most significant for beginning the "He will knock four times" story arc, ultimately resolved in The End of Time.
 * Behind the scenes, it featured a revolution in the way Doctor Who was filmed. Beginning with this episode, Doctor Who episodes were natively recorded in high definition. Likewise, the home video release of Dead was the first episode of Doctor Who ever released in the Blu-ray format. The story also broke new ground with its location filming, which involved Doctor Who's first road trip to an Arabic country. Finally, it was Tracie Simpson's debut as a full producer, after having risen up through the production ranks since starting as a production manager on Rose.
 * As seen in David Tennant's video diary for this episode's read-through, Tennant feared that, having spent six months portraying Hamlet for the RSC, he would be unable to accurately replicate the voice he uses when portraying the Doctor. In an informal discussion with Julie Gardner, he describes his voice for Hamlet as being the same as the Doctor's (being an English accent) except "more posh" and mentioned he may have to watch his previous performances as the Doctor and practice the voice. This strongly echoes Billie Piper's dilemma when she returned to film Turn Left: in interviews with Doctor Who Confidential, Piper confessed to having forgotten how to speak in Rose's accent; it was later noted that she spoke with a noticeable lisp in several scenes of that episode.
 * As revealed in Doctor Who Confidential, Ryan performed most of her own stunts in the episode — including the high-wire stunt that opens the episode.
 * Part of the episode was filmed in Dubai, United Arab Emirates. A bus that was to be used for filming there was heavily damaged upon arrival there.
 * According to the BBC report, the damage to the bus — a twin to one being used for filming in Cardiff — prompted a rewrite of part of the script to add a few references to the bus being damaged going through the wormhole.
 * On 16 January 2009 The Guardian newspaper published an online column condemning the then-rumoured plan to film in Dubai, citing the UAE's human rights record. Similar criticism was posted by the fan site Kasterborous on 28 January.
 * Planet of the Dead was the first Doctor Who story to be produced in high-definition. As such, it features a more detailed, but otherwise unchanged, version of the title sequence.
 * According to Tennant's video diary, he and co-star Adam James have been friends for 10 years, having also worked together in the past. James is also Jon Pertwee's godson.
 * In an interview for BBC Breakfast on 7th April 2009, Russell T Davies revealed that the episode had only been completed at 11:30pm the previous night, only 5 days before the episode aired.
 * In pre-broadcast publicity interviews, Michelle Ryan described her character as a one-off companion, though like most other one-offs, such as (initially) Donna Noble and Jenny, the door has been left open for a future return. Prior to the announcement that Karen Gillan had been cast as the new ongoing companion, Ryan was listed among possible candidates.
 * Although the Doctor has had invitations to join him turned down by potential companions in the past (Grace Holloway in the 1996 TV movie, Mickey Smith at the end of World War Three and, initially, Donna Noble in The Runaway Bride, for example), this is one of the few occasions in which the Doctor has outright refused to take on a companion of his own volition, despite clear indications of compatibility. This also occurred with Mr Copper in Voyage of the Damned, and for much the same reason the Doctor gives Christina.
 * This story went through several drafts. These included a space opera about a giant war (possibly featuring the Chelonians); a bizarre story about time-freezing centaurs in a deserted hotel; a Star Trek pastiche; and a story about an outer space hotel where guests were disappearing - taken down to the planet below in order to be implanted with alien eggs.
 * This is the first Doctor Who episode in which series producer Russell T Davies shares co-writing credit, and the first episode since the show's return in 2005 to credit two writers. The last televised story to credit two writers was the 1993 mini-episode Dimensions in Time.
 * This story was nominated for a 2010 Hugo Award in the category of "Best Dramatic Presentation, Short Form," as was The Next Doctor and The Waters of Mars, the latter of which ultimately won the award.
 * In this special, Christina becomes the next on the list of companions who have kissed the Doctor. By this time, on-screen kisses included: Dr. Grace Holloway, not long after his seventh regeneration; Jack Harkness, who gave the Doctor (and Rose) a farewell kiss on the Gamestation; the Doctor kissing Rose Tyler later in the same episode; Cassandra kissing the Doctor while possessing Rose Tyler's body; Jackie Tyler kissing the Doctor three times when he and Rose returned home in the middle of the ghost crisis; the Doctor kissing Martha Jones to confuse the Judoon's scanners; Astrid Peth kissing the Doctor twice whilst on the Titanic; and Donna Noble kissing the Doctor to give him a shock when he needed to use his Time Lord physiology to detox from cyanide poisoning.

Ratings
The BARB official ratings are 9.54 million, the 5th most watched programme of the week, the second most watched on BBC of the week and the second most watched of Saturday 11th April. It also gained 200,000 viewers on BBC HD, the biggest ever audience for the channel. Planet of the Dead is now the sixth best rated Doctor Who episode since its 2005 revival with Voyage of the Damned, The Next Doctor, Rose, Journey's End and The Christmas Invasion beating the episode.
 * Easter Saturday 11th April 2009 ~ 6:45pm ~ BBC One ~ 8.41 million (unofficial overnight)
 * This story refers to the events of when the Earth is transported to the Medusa Cascade that took place in May - June 2009, based on novel information, which would place it in 2010; however, controversy erupted with TV: The End of Time taking place on Christmas 2009, placing this story in Easter 2009 before the Medusa Cascade incident. Unfortunately, there are many reasons this story cannot take place after The End of Time, some of which are Naismith's status and the worldwide recession. The writers or producers have not addressed the dating issue. Some fans believe what date novels give should only be taken with a grain of salt if it disturbs on-screen continuity.

Rumours

 * Carmen mentioned that "Your song is ending," leading to people believing it could refer to River Song. The first part of the prophecy referred to the Tenth Doctor's life.
 * People thought that "It is returning through the dark" referred to either Davros, who presumably died two episodes prior, or Gallifrey. It was indeed Gallifrey.
 * People thought that the four knocks referred to either the Midnight entity or the Master returning. In fact, the four knocks referred to Wilfred Mott knocking on a glass door four times when trapped, an event that would lead to the death of the Tenth Doctor. The Master did return, however.
 * Since eccentric time lady Iris Wildthyme had a TARDIS that resembled a London bus, there were rumours she'd appear in the special.
 * Related to the Wildthyme rumour, speculation regarding the identity and true nature of Lady Christina, following statements by Davies that she would have a profound impact on the Doctor, included the possibility that she might be a Time Lord, and perhaps even a known Time Lord such as Romana. This ultimately proved not to be the case, although the Doctor's comment to Christina that "You look Time Lord" referred to the fact that humans and Time Lords look alike; however, Time Lords came first. There are, in fact, many situations where fans believe a character is a Time Lord, but it never turns out to be true.
 * It was rumoured this episode would feature the Nimon, because they were mentioned in the commentary by Russell T Davies for The Next Doctor and are known to suck the life out of planets.
 * Before Russell T Davies announced the episode's title as Planet of the Dead, it was rumoured that the episode's title was Transport of the Doomed.
 * The post-credits trailer for the upcoming special The Waters of Mars is set to the sound of the cloister bell tolling, foreshadowing the peril it will host.

Filming locations

 * Cardiff, St Mary Street - the first scenes with the red bus driving down the road with the Doctor and Christina stepping on to it
 * Cardiff Bay - Police and UNIT investigating the disappearance of the bus through the wormhole
 * Dubai, United Arab Emirates - San Helios
 * Cardiff ~ Butetown Tunnel - Queens Gate ~ A4232

Production errors

 * When the bus is originally shown, it has a number plate of W974GHM, but later, when flying, its number plate has changed to RUA461W.
 * When Lady Christina climbs back up after stealing the cup of Athelstan, she is on the roof, but in the next scene she is still inside.
 * When Malcolm opens the trailer door after he closes the wormhole, the glass in the door is the wrong way around as it spells T.I.N.U from the outside.
 * When the Doctor is "tinting" his glasses with his sonic screwdriver, he lowers them out of view. When he lifts them back into view, the tortoise shell colouration of the stems and frames on his glasses is black, revealing that sleight-of-hand camera tricks were used to hide an obvious switch between two different sets of glasses. It is possible the sonic screwdriver can also blacken the colouration of the framework on the glasses.
 * At around 20:48, a stray fly in the desert can be seen skittering on the Doctor's tie and flying off. San Helios is meant to be completely devoid of life.

Continuity

 * A flying bus previously appeared in TV: Delta and the Bannermen.
 * Several bus passengers discuss the events surrounding the relocation of Earth to the Medusa Cascade. (TV: The Stolen Earth/Journey's End) Angela says "It's impossible, there are 3 suns, 3 of em!" and Barclay replies "Like when all them planets were up in the sky!", to which Nathan says "But it was the Earth that moved then, wasn't it?".  Barclay realizes "Oh man we're on another world."  This also clarifies that the general population is now quite familiar with and can properly recognize the various alien interventions that more and more constantly beset them.
 * The advert on the side of the bus is for Neon by Naismith, a phone company owned by billionaire Joshua Naismith. (TV: The End of Time)
 * The Doctor mentions, "Humans on buses, always blaming me", referring to TV: Midnight.
 * The Doctor mentions the K1 Robot when asking Malcolm what his favourite file about him was. (TV: Robot)
 * Carmen says, "Your song is ending", which is what the Ood also said to the Doctor in TV: Planet of the Ood. As well as the warnings of darkness heard in Series 4, (Turn Left, et al) the reference to knocking reflects a similar event that occurred in TV: Midnight.
 * An alternate reality Captain Magambo appeared in Turn Left and helped Rose Tyler and an alternate Donna Noble set history right.
 * Christina refers to the economic crash of 2008. Unbeknownst to the general public, the ensuing recession was caused by a British teenager named Theo Lawson hacking into several multinational banks and acquiring enough money for the rest of his life. The Eighth Doctor met Lawson in London shortly before his death in 2010. (AUDIO: Situation Vacant) The recession was over by Christmas 2009. (TV: The End of Time)
 * Malcolm named his unit of measurement the Bernard after Professor Bernard Quatermass. The British Rocket Group, to which Quatermass belonged, was previously referenced (as was Quatermass himself, vaguely) when the Doctor was in 1963 London. (TV: Remembrance of the Daleks)
 * When Captain Magambo tells the Doctor it is an honour to serve him during a phone conversation, he gets the notion she has saluted him over the phone, which she hastily denies. The Doctor has previously been saluted by UNIT and has repeatedly asked them to stop doing so. (TV: The Sontaran Stratagem)
 * The Doctor's TARDIS is discovered in the gardens of Buckingham Palace, and according to the Doctor, "she doesn't mind". It is unclear whether he is referring to the Queen not minding its presence or the TARDIS not minding the fact that it had been left in the gardens of Buckingham Palace. Previous stories implying that the Doctor and Queen Elizabeth II know each other and are on good terms include Silver Nemesis and Voyage of the Damned.
 * A reference was made to Donna Noble as the Doctor said he had a friend who called him "Spaceman". (TV: Journey's End, et al)
 * The Doctor says Christina looks Time Lord in response to her saying that he looks human. The Eleventh Doctor would later say the same to Amy Pond. (TV: The Beast Below)
 * The Doctor tells Christina of some of the eras he's visited: World War I, the creation of the universe, the end of the universe (TV: Utopia), "the war" between China and Japan (exactly which war is not specified; possibly a reference to the conflict predating World War II), and the court of King Athelstan in the 10th century AD.
 * The Captain expresses her surprise that "guns work" on the Swarm. As the Brigadier once lamented, UNIT's enemies generally have an immunity to bullets. (TV: Robot)

Home video releases
Planet of the Dead was released on DVD and, for the first time for a Doctor Who episode, on Blu-ray in the United Kingdom on 29th June 2009. The release includes a single bonus feature:


 * Doctor Who Confidential - unlike previous DVD releases, this is a complete, 60-minute version, including licensed music and clips from both the classic series and the 1996 TV movie.

In North America, the DVD and Blu-ray were released on 28 July 2009. The release is identical to the Region 2 version, including the intact Confidential, even though it includes clips from the 1996 TV movie which at the time could not be released in Region 1 due to licensing issues.

In Australia, the DVD was released on 29th of June 2009, Blu-ray on 1st of October 2009 and included the same special features as the UK release.

This is the first Doctor Who episode to ever be released on the high-definition Blu-ray format.

The four specials plus The Next Doctor were released in the UK on both DVD and Blu-ray in a box set in January 2010, with a North American release scheduled for 2nd February 2010.

This episode is listed as episode 16 of Series 4 on Netflix in the US. Previously, it had been listed as a separate standalone title, before vanishing from the service entirely some time in 2011. It reappeared on Netflix in 2014, concurrent with the additions of The Day of the Doctor and The Time of the Doctor to the service.

International broadcast
The Canadian cable network Space aired the special on July 25th, 2009 in an 85-minute timeslot (including commercials) with minimal edits, the most noticeable being the omission of the trailer for The Waters of Mars. As a result of the edit, the episode ends uniquely, with the traditional "howlaround" sound replaced instead with a single tolling of the cloister bell.

BBC America aired the special on 26 July as part of the rollout of its new HD service. This marks the changeover for Doctor Who from broadcasts on Syfy to BBC America, which has taken over first-run broadcasts of the series.