The action within "Voyage of the Damned" takes place immediately after an extremely difficult series of events for the Doctor. He has caught up with Captain Jack (who is now immortal), met the Master again, had his TARDIS stolen and pimped out as a paradox machine, been physically aged, turned Martha from a doctor into a secret agent, been transformed back into his usual self, lost the Master (and therefore reopened all the wounds about being the last remaining Time Lord), said goodbye to Martha and then—in a parenthetical moment seen in "Time Crash," the Doctor Who Children in Need special—met his Fifth incarnation and discovered that the TARDIS has been crashed into by something that claimed to be the Titanic.

That he does not just dematerialize for a long lie down and then come back to explore a little better says a lot about his natural curiosity and unearthly energy levels.

Here are a few things that you should keep an eye out for, the next time you watch what happens next.

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Kylie Minogue's appearance as a one-off companion came through a mutual admiration pact between Doctor Who and her production team. Will Baker, the creative director for her tours, had snuck some Whovian references into her stage act, including Cybermen and Raston Warriors (from "The Five Doctors"). The script for "The Idiot's Lantern" mentions Kylie appreciatively. So, having attended a press launch for Season Three with Mark Gatiss, Will suggested a Kylie guest appearance, which Russell T Davies was quick to see would allow a transition of companions from Martha to someone else, a character he had given the name Penny, at the time.

Kylie was not the only notable guest star lined up for this story. Multiple sources claim that Dennis Hopper, star of movies such as Easy Rider, Rebel Without a Cause and Blue Velvet, had been interested in playing Mr. Copper. There was also a report in the British tabloid The Sun, claiming that Woody Allen would be appearing as Albert Einstein, but neither cameo came to pass.

https://www.youtube.com/watch?v=z8lBEoPi6OY

In Russell T Davies' original draft, Foon Van Hoff was called Struzie, Midshipman Frame's surname was originally Blane, and Astrid Peth was known as simply Peth. Max Capricorn was initially Mr Maxitane and then Max Callisto. His life support machine hadn't been brought in by this point either, and he was to have appeared alongside the other passengers during the ballroom scenes at the beginning, and his comeuppance would not have been at the expense of Astrid's life either.

Even the title of the story was different first time around, Davies had gone with Starship Titanic as a title, before discovering that Douglas Adams had already created a computer game with the same name, that was released in 1998.

Another element that had to be changed was the final swoop towards Buckingham Palace, in which the Doctor rings up and has the Queen evacuated in her slippers. Originally the ship was to destroy the Palace, much as the Slitheen spaceship did for Big Ben in "World War Three," and the Queen was to have cursed the Doctor (just as her forbears Elizabeth I and Victoria did), and even mooted the idea of a cameo appearance by Prince Charles. In the end, the spirit of festive goodwill prevailed.

When the passengers of the Titanic visit Earth, one of the road signs is for "Donovan Street."

https://www.youtube.com/watch?v=fKEbG34auGs

This was an affectionate reference to Jason Donovan, the actor and pop star who had played Kylie Minogue's on-screen husband in the Australian soap Neighbours, and sang this memorable duet with her in 1988:

https://www.youtube.com/watch?v=aGuNsiSZ9RI

Season Three of Doctor Who has a hidden thread running through it, sometimes intentional, sometimes not. References to angels kept popping up. There were, of course, the Weeping Angels in "Blink," but also the Archangel Network in "The Sound of Drums" and "Last of the Time Lords" and the robotic butlers called the Host in this episode, which take the form of golden-headed Angels (and look a lot like the robots in the Fourth Doctor story "The Robots of Death"). The Doctor himself is referred to "my lonely angel" in the Season Two story "The Girl in the Fireplace," and when Murray Gold was asked to write a Broadway-style song for Tallulah to sing in "Daleks in Manhattan," he came up with "My Angel Put the Devil in Me."

Speaking of Murray Gold, he made a guest appearance, alongside his arranger Ben Foster in the ship's band, behind singer Yamit Mamo. Yamit sang "My Angel Put the Devil in Me," and this episode's "Winter Wonderland" and the Irish folk-influenced number "The Stowaway"—surely a nod to the lower deck dancing scenes in the movie Titanic.

Both Clive Swift (Mr. Copper) and Geoffrey Palmer (Captain Hardaker) had previously appeared in classic Doctor Who. Clive played Jobel in the Seventh Doctor story "Revelation of the Daleks," while Geoffrey had appeared twice. Once as Undersecretary Masters in the Third Doctor story "The Silurians," and shortly afterwards as the Administrator in "The Mutants." Colin McFarlane, who gave the Heavenly Host their communal voice, recently made a return trip to the show, playing Moran in "Under the Lake."

And finally, there's a moment where the broken Host gets stuck on the word "Max", which is a nod towards the character Max Headroom, the partly computer generated TV host created in 1984.

https://www.youtube.com/watch?v=nt56RMbpq_0

This would be good enough as a hidden reference for fans to spot, were it not for the existence of a previous point of crossover between Max and Doctor Who. On November 22, 1987, an episode of the Fourth Doctor adventure "Horror of Fang Rock," broadcast on WTTW in Chicago, was interrupted by this bizarre pirate broadcast, involving someone in a Max Headroom mask talking indistinctly:

https://www.youtube.com/watch?v=GGqkcKU0wf4

The perpetrators were never discovered.

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