Roots: The idea of revisiting a parallel universe was explored in several episodes of Star Trek: Deep Space Nine, and in The Face of the Enemy (a Who story which also sees time move on more quickly in the alternative universe than in the "real" one). Dalek/Cybermen battles have been a genre within fan fiction for decades, and one was proposed for the abortive early-90s film The Dark Dimension. The use of Canary Wharf is reminiscent of Millennial Rites. The Doctor's comment about living life one day after the next is slightly reminiscent of the Doctor's parting words to Mel in Dragonfire. The dimensional jumps are reminiscent of The Tomorrow People.
Goofs: The Tardisode shows a Dalek invading a news studio to announce that they are the masters of Earth, an event for which there is no space within the episode.
The Cybermen claim that the Daleks' design is inelegant. Surely that's an emotional judgement they shouldn't be capable of making. [They mean inefficient compared with their own.]
How do the Cybermen know that Daleks and Cyberman technology is compatible?
If there are only five million Cybermen, then surely their occupation of Earth can't be as total as was implied in the last episode and at the start of this one. Also, it would be a serious waste of resources to have Cybermen occupying homes, as seen in both episodes, with this few troops relative to the global population. [They are more concentrated in London, and hence begin upgrading the population there.]
How do the Daleks recognise the Doctor as an enemy when they can't have seen this incarnation before, and are surprised when Rose tells them that he is the Doctor?
How does Yvonne conclude that the Cybermen upgrade by removing the brain? [Mickey left a report in Torchwood files which led her to that conclusion.]
In The Parting of the Ways and The Children in Need Special (Pudsey Cutaway / Born Again), Rose had no memory of anything between looking into the heart of the TARDIS and waking up after the Doctor had drawn the vortex energy out of her, yet here she remembers how she destroyed the Emperor Dalek.
When the Time Lords imprison several million Daleks, why did they leave those Daleks fully armed? Surely that's just asking for trouble. [Perhaps it's to do with the way they imprisoned them. If the prison was actually a method of capturing Daleks, they wouldn't have time to disarm them first.]
How does Yvonne overcome the Cyber conditioning when not one of the thousands converted in The Age of Steel was able to do so? [Mickey left a report in Torchwood files which gave her the knowledge of how to do so.]
The last things to fall into the breach before Rose are Daleks. As all the Daleks were within a few miles of the breach whilst the Cybermen were scattered across the world, surely the vast majority of the Cybermen were left behind. [In the commentary, RTD said that they were sucked through the fault lines that they had originally come through, which then begs the question of why all the ones we saw were lifted up into the air when all the cracks through which they appeared were at ground level, or within buildings. Two possible explanations are that interference from the Earth's magnetosphere made it easier for them to be pulled into the fault lines by being lifted off the ground, or that the breach pulled in those who were further away an awful lot faster.] Furthermore, some of the Cybermen were constructed in the "real" London, and wouldn't have had voidstuff on them. [They were constructed using parts that had been brought across, or their numbers were so few that they were easily defeated.] Also, why wasn't the TARDIS dragged through? [It used one of its defence systems to temporarily leave this time zone.]
Why does Pete suddenly change his mind about jumping back to retrieve Rose? And how does he manage to arrive at just the right time and place to save her from being sucked into the void?
Dialogue Triumphs: Cyberleader: "Daleks be warned. You have declared war upon the Cybermen."
Dalek Sec: "This is not war. This is pest control."
Cyberleader: "We have five million Cybermen. How many are you?"
Dalek Sec: "Four."
Cyberleader: "You would destroy the Cybermen with four Daleks?"
Dalek Sec: "We would destroy the Cybermen with one Dalek. You are superior in only one respect."
Cyberleader: "What is that?"
Dalek Sec: "You are better at dying."
Rose: "Five million Cybermen, easy. One Doctor? Now you're scared."
The Doctor on Daleks: "Sealed inside your casing. Not feeling anything, ever. From birth to death, locked inside a cold metal cage. Completely alone. That explains your voice. No wonder you scream."
Continuity: The Daleks can extract information from somebody's brainwaves using their plungers, this causes the victim to die. They are aware of the design of [this universe's] Cybermen. They have long range scans which can detect "crude cybernetic constructs" worldwide [but presumably not the Dalek in Van Statten's bunker - see Dalek]. The Doctor says that their "skin" is made of Polycarbide. They have names: the Black Dalek is Dalek Sec, the others are Dalek Thay, Dalek Jast, and Dalek Caan. They are part of the Cult of Skaro - a secret order above and beyond even the Emperor. Their job was to imagine, and think as the enemy thinks. They are capable of overriding the roof controls of Torchwood Tower. Dalek Sec has the ability to initiate an emergency temporal shift, allowing him to escape.
The Genesis Ark is a prison constructed by the Time Lords to hold millions of Dalek prisoners and is bigger on the inside than it is on the outside. They say that it is all that survives of the Time Lords' homeworld. It needs an area of 13 square miles, which gives some idea of how many Daleks are imprisoned within it.
The Cybermens' energy weapons are incapable of penetrating a Dalek's personal forcefield. If you kill one of their Cyberleaders, they just download into another Cyberman, upgrading it. The alt-world humans sealed the Cybermen into their factories, but people argued that they were living beings. During the debate, the Cybermen infiltrated Torchwood, and disappeared. This was three years ago. In the last sixth months, average temperature has risen by two degrees.
The alt-universe's Torchwood developed universe-hopping technology like they Cybermens'. Their version of Torchwood was found out and the Peoples' Republic took control. Jake and Pete are now involved in Torchwood.
Rose expands on the energy that awakened the Dalek in Dalek. Time travellers soak up harmless background radiation [artron energy]. The Daleks evolved to use it as a power supply during the Time War.
The Daleks initially identify the sonic screwdriver as a sonic probe.
The Doctor modifies Jake's gun to impair a Dalek's personal force field.
Anybody who has been through the void will have voidstuff floating around their body - even travelling through it in a TARDIS or a voidship does not prevent this. The Doctor's "3-D glasses" allow you to see the voidstuff.
Pete has an old Jeep. Rose is on the list the dead compiled after the battle. After moving to the alt-universe, she started working for alt-Torchwood. Jackie is three months pregnant by the time Rose receives his message.
The TARDIS requires the power of a supernova to send a message through the last part of the breach - the Doctor literally burns up a star to send a final message to Rose.
Links: Rise of the Cyberment/The Age of Steel. Rose recalls the Dalek in Dalek. Harriet Jones (Aliens of London, World War Three, The Christmas Invasion) is now President of the alt-Universe Britain, and it's being called the global age. The Doctor mentions knowing Pete Tyler when he was dead, and being at Pete and Jackie's wedding (Father's Day). Rose mentions the fate of the Emperor Dalek in The Parting of the Ways. The Doctor mentions Arcadia (Deceit).
Extras: This story has an episode of Doctor Who Confidential. The BBC created a one-minute trailer called a "Tardisode" for each episode of series two, which was available to download on your mobile or watch at the BBC website. They also made a commentary track available online, and with the red button during the digital repeats. Neither is still available on their website.
Location: Canary Wharf, c. 2007 and also Pete's universe over three years since The Age of Steel. Jackie says that Pete died 20 years ago. Dårlig Ulv Stranden at least three months later.
Unrecorded Adventures: The Doctor says that he survived the Time War by fighting on the front lines. He was there at the fall of Arcadia (and says that some day he might even come to terms with that event).
Q.v. Bad Wolf, The Parting of the Ways
The Bottom Line: A decent conclusion to the series. The Dalek/Cyberman battle is a fanboy's dream come true, and the Daleks are shown to be far superior, just as they should be. Everybody's well written and acted, and the departure of Rose is exactly what we've come to expect from the new series emotionally. However, the final scene with Catherine Tate completely ruined the ending.