Russell T. Davies used Bernard Cribbins own military experiences as the basis for Wilfrid's reminiscences. The only difference being that the actual blizzard that the actor endured became a metaphorical blizzard of bullets for Wilf.
Director Euros Lyn wanted to remove the scene where the Doctor visits Verity Newman, thinking it would be confusing for anyone who had missed the connection she has to the Doctor, but Russell T. Davies insisted on keeping the scene in the final cut.
The scene where Luke is saved is part of an in-joke, according to Russell T. Davies. In the first series of The Sarah Jane Adventures (2007), none of the children characters looked where they were going whilst crossing the road.
The alien bar where Captain Jack is drinking was inspired by the cantina from Star Wars: Episode IV - A New Hope (1977). It is also based on the original concept for The Shadow Proclamation in "The Stolen Earth".
In the scene where The Doctor gives Jack Harkness Alonso's name, the music playing is "My Angel Put the Devil in Me" that was featured at the beginning of Season Three episode, Doctor Who: Daleks in Manhattan (2007).
Russell T. Davies originally considered having the Time Lords in an alliance with the Daleks to show how they had been corrupted. However, Steven Moffat was also planning to bring back the Daleks and expressed his preference for this to be the first Dalek story in a while. Keen not to undermine his successor's first season, Davies abandoned the notion.
During the chaotic sequence after the regeneration, the Eleventh Doctor is shown spitting, an act that raised some eyebrows. In addressing this during a publicity event for the launch of Series 5, Smith explained that it was his natural reaction to all the debris raining down on him during the filming, while Steven Moffat indicated that Russell T. Davies chose to leave it in.
There was originally a scene where the Doctor actually met Trinity Wells, the American news anchor who had appeared intermittently ever since "Aliens Of London". Russell T. Davies was eager to give Lachele Carl a proper appearance in the series, but ultimately dismissed the sequence as too self-indulgent.
Originally, much of the Vinvocci's faces retained their natural human skin tones, but it was now decided that they should be completely green; sequences featuring the aliens which had already been recorded would be computer-tinted to match the revised look.
At the beginning of the episode, Rassilon mentions the Doctor is still in possession of the Moment. This was the Time-lord Super weapon that appeared in the 50th anniversary special, in which the War doctor was going to use it to end the Time War.
The Tenth Doctor is shown looking in on all of the companions that appeared during his tenure before he regenerates. In The Sarah Jane Adventures, the Eleventh Doctor reveals that he didn't just visit the companions he had known as the Tenth Doctor, but every companion he had ever had.
In Doctor Who: The End of Time: Part Two (2010), the evil Lord President of the Time Lords is revealed as Rassilon, the founder of Time Lord society. In Doctor Who: The Five Doctors (1983), The Second Doctor tells Brigadier Lethbridge-Stewart that there was a rumor that the Time Lords had rebelled against his cruelty and imprisoned him in the Black Tower (Rassilon's final resting place). In the back-story of Rassilon's appearance in the 2-part special, Rassilon was brought back from the dead to lead the Time Lords in the Last Great Time War. But The War Doctor foiled Rassilon's plot to use The Tear of Isha to wipe out The Daleks from the Tantalus Eye and had condemned The Doctor as an enemy of The Time Lords and had planned to save Gallifrey from destruction by using the Ultimate Sanction turn the Time Lords into beings of pure consciousness, only to be time-locked by The Doctor.
In an early draft of the script, Russell T. Davies had the Doctor address the "half-human" statement the Eighth Doctor made in Doctor Who (1996), dismissing it as "a forty-eight-hour bug". The line was cut by Davies for several stated reasons, including the fact it would have confused viewers who were only familiar with the events of "Human Nature".
One prominent element dropped from the script was a subplot in which the Doctor tries to convince the "Danes-Master" (that is, the copy of the Master who had been Danes, the Naismiths' butler) to rebel against the evil Time Lord.
The scene in which The Doctor says "I don't want to go." was filmed four times, each with increased level of intensity in the delivery. The take which made it to air was the third take, as the fourth and final take was considered to be too emotional.
Russell T. Davies said that the Tenth Doctor's last moments were planned out shortly after David Tennant was cast in the role, and implied that had Tennant not been cast, the scene would have been written differently.
Before regenerating, The Doctor meets Rose Tyler again on January 1st 2005 months before The Doctor and Rose first met. It explains Rose's reaction when The 9th Doctor regenerated in (#1.13), when she sees The 10th Doctor for the first time.
The Master redeems himself by sacrificing himself and saving the Doctor. According to historical accounts of the production of the classic series, this idea dates back to the original concept for Jon Pertwee's final story as the Third Doctor The Final Game, which would have seen Roger Delgado's Master redeem himself in a similar fashion (it would also have caused the Doctor's regeneration). Delgado's tragic death aborted this idea.