The medical student Martha Jones (Freema Agyeman) has spent the previous year travelling the planet as part of a plan to stop the Master.
She has been preparing the surviving humans to concentrate their thoughts on the word "Doctor" the moment of the completion of the countdown to the launch of a fleet of rockets the Master is readying to wage war.
Martha reveals the gun to be a hoax, and her travels to have been with the aim of focusing the collective psychic energy of the people to think of the Doctor.
As the Doctor prepares to travel, the bow of a ship called the Titanic bursts through a wall of the TARDIS control room.
[2] The hand seen picking up the Master's ring was included in order to leave open the possibility of reintroducing the character at a later date.
[5] This episode was planned to be broadcast live to the crowds attending Pride London in Trafalgar Square via a giant screen.
In the audio commentary, the producers reveal that Graeme Harper filled in to direct some scenes after director Colin Teague was injured.
At the start of this episode, The Master enters the bridge of the Valiant as "I Can't Decide" by the Scissor Sisters plays in the background.
The audio commentary for the episode mentions that Leo was originally scheduled to appear in the sequence showing Martha's return to Britain, but Yates was double-booked.
"[16] SFX reviewer Dave Golder gave the episode three and a half out of five stars, concluding that it was "Good solid fun, with some great performances and memorable visuals but possibly the least satisfying New Who finale so far".
Though he thought there was "loads to enjoy" such as John Simm as the Master, Freema Agyeman's performance, and the effects, he wished to explore more of the dystopian world and said of the conclusion, "I liked the message it was trying to get across, but the shots of a ghostly Tennant floating down the steps did unfortunately look like something out of a panto.
[18] Mark Wright of The Stage called it the "weakest of the season finales for Doctor Who to date", with much of the plot being "lazy" or not making sense and "[played] out as silly and lacks substance".
While he praised Martha and the emotional climax, he found Jack "criminally underused" and criticised the representation of the aged Doctor.