A four-part version of this story was shown from 14 to 17 August 1984 at 6.15 p.m. on BBC One.
When he meets Colonel Crichton, the second Doctor claims his replacement was a disappointment. This refers to the contentious relationship the two incarnations had in The Three Doctors.
Plot Hole: Borusa commands the companions to stay still. They do — except for the Brigadier, who turns his head to watch Borusa as he moves across the room.
Plot Hole: When the Cybermen arrived in the entrance hall, they look right at the Doctor and Tegan but apparently ignore them.
Revealing Mistake: After the Raston Warrior Robot has destroyed all the Cybermen, it disappears. When it does so, several of the dead Cybermen shift their position.
When the Master is transmatted into the Death Zone he is wearing only his black suit with the embroidered collar. When next seen in the Death Zone he is now wearing a cloak over his clothes. Where did he get it?
What appears to be a goof was most likely the result of Jon Pertwee stealing another character's line. Sarah Jane was supposed to have told the Third Doctor he changed into all "teeth and curls." According to the DVD running commentary, Terrance Dicks claims that Pertwee liked the line so much he pilfered it for his own. The line appears to makes no sense when the Third Doctor says it, though, as it suggests foreknowledge of his future incarnation.
When the homing beacon is revealed in the TransMat recall device given to the Master, the Castellan claims he's being framed by the Doctor for revenge. Why exactly? This could be a reference to events in Arc of Infinity, where the Castellan is played by the same actor.
On the DVD release's commentary, writer Terrance Dicks claims that he wrote the First Doctor's "solution" to the checkerboard puzzle, pretty much, off the top of his head., and that he has been asked to explain it, even though he wrote it purposefully with no answer. (The novelization even makes an aside that the Doctor never bothered to explain what the solution was.) At first glance, it seems impossible that he could have used the mathematical formula for Pi, the circumferance of a circle divided by its diameter in Euclidean geometry, to solve a problem based on a square. However, Pi can also be a constant expressed in relativity, something the Doctor should know a lot about. In that way, it can also be defined using an infinite series such as Pi/4 = 1 - 1/3 + 1/5 - 1/7 + 1/9 - ... In general relativity, space and spacetime are expressed as non-Euclidean geometries. In a non-Euclidean geometry, circumference divided by diameter can be more or less than Pi. Non-Euclidean geometries are used in physics, so the ratio is very nearly Pi over small distances i.e. any finite value divided by infinity is so small it might as well be 0, so it is called 0. Thus, over small distances, there are relatively unnoticeable differences in the measurements for Pi. The Doctor could well have been working in a non-Euclidean geometry for the puzzle's solution, but, Pi would still be roughly the same value, as he states, 3.14159265. Dicks just stumbled into this by blind luck, most likely, and it still doesn't explain what the puzzle solution is, though.
Borusa and the Fifth Doctor beam to the tomb of Rassilon via the transmat terminal, which begs the question of why he transported the Doctors and their companions to the Death Zone to contend with his worst enemies in the first place. The Doctor states that they deactivated the defences around the Tomb, allowing Borusa in. In the extended edition, Borusa, sounding somewhat mad, adds that it was a game within a game — played out for his amusement.
In the original script, the Doctor looked around the room to find the secret switch that is always hidden in such rooms to open the door. But Script Editor Eric Saward thought that wasn't clever enough and introduced the idea of the musical lock, with the key to the puzzle contained in a painting in the room. Such devices are a favourite of Borusa's: saying "There's nothing more useless than a lock with a voice print" twice opens a voice-activated lock in The Invasion of Time.
During the scene inside the TARDIS where the Fifth Doctor tells the First Doctor that he plans to enter the main door of the Tower, the younger Doctor seems quite adamant that Tegan stay with him, for her safety. Yet, he doesn't seem to mind that his own granddaughter is going to jaunt off into danger with Turlough and the Fifth Doctor. It seems he would more likely to want Susan to stay behind with him.
Why did the Warrior Raston Robot have ropes conveniently stored with its extra arrows and ammunition? Not only ropes, but hand-looped nooses to hold on to for sliding across the ropes with!
The Master tells the Cybermen that the safe path across the chessboard in the Dark Tower changes with every journey taken across it. If that is so, how does one figure out what the safe path is? After the trap has been triggered by the advancing Cybermen, there is nothing to indicate any change in the board, save for Cyber-bodies. When the Master first crosses the board, he simply walks straight across it. Then, when the First Doctor figures out the Pi reference, he, too, manages to cross over the trap by just walking straight across it!
The Master has to dodge all sorts of energy beams from the sky above the Death Zone. The last of the energy beams is superimposed late, and we see a small explosion on the ground before visual effects draw in the energy beam. This error has been corrected in the DVD version of the episode.
What is the scale on the TARDIS computer scanner? Turlough and the First Doctor observe the scanner and find traces of the Second and Third Doctors very close together. But the Second Doctor, backed by the Brigadier, and the Third Doctor, towing Sarah Jane, approach the Dark Tower from different angles and head for different doors.
The Second Doctor deduces that Jamie and Zoe must be phantoms because their memories were wiped by the timelords when they left him. However, they were both left with memories of their first adventure with the Doctor. In any event, this is inconsistent with an apparently older Second Doctor travelling with Jamie and Victoria in The Two Doctors.
Fifth Doctor: I am definitely not the man I was. Thank goodness…
Sarah Jane[ to the Fifth Doctor ]: Goodbye. It was really nice meeting you.
Third Doctor: Thank you, Sarah Jane. It's nice meeting you, too.
Brigadier: Goodbye, Doctor.
Fifth Doctor: Goodbye.
Third Doctor: Goodbye, Brigadier.
Brigadier: Splendid fellows. All of you.
Second Doctor: Goodbye… fancypants!
Third Doctor: Scarecrow!
First Doctor [ to the Fifth Doctor ]: Goodbye, my boy. You did quite well, quite well. It's reassuring to know my future is in good hands.
Second Doctor: So, you're the latest model, hmmm?
Fifth Doctor: Yes, and the most agreeable.
Second Doctor: Oh, certainly the most impudent.
Third Doctor: And our dress sense hasn't improved much, has it?
First Doctor: Neither have our manners.
The Master [ holding the first three Doctors at gunpoint ]: Killing you once was never enough for me, Doctor. Oh, how gratifying to do it three times over!
Second Doctor: Have faith, Brigadier. Have I ever led you astray?
Brigadier: On many occassions.
Second Doctor: Yes, well, this will be the exception.
Tegan: What do you want?
The Master: To help.
Tegan: That's the funniest thing I've heard all day.
Sarah Jane: Do you think this is wise, Doctor? I mean, whatever's in that tower, it's got enormous powers. What can we do against it?
Third Doctor: What I've always done, Sarah Jane: improvise.
Sergeant: I'm sorry, sir. You're not allowed in there.
Second Doctor: Not allowed? Me? I'm allowed everywhere!
Brigadier: I can't tell you how much I was looking forward to this reunion. The chance to re-meet old friends.
Crichton: There was one chap we tried to get hold of… what was his name? Used to be your scientific advisor?
Brigadier: Oh, the Doctor?
Crichton: Yes, that's right.
Brigadier: Wonderful chap. All of them.
Fifth Doctor: The TARDIS is more then just a machine, Tegan. It's like a person. It needs coaxing, persuading, encouraging.
Tegan: You mean it's just as unreliable.
The Third Doctor: To lose is to win, and he who wins shall lose.
The Second Doctor (Sings): Who to Rassilon's Tower would go
Must choose above, between, below.
The Brigadier: Are you in pain, Doctor?
The Second Doctor: Age has not mellowed you, has it, Brigadier? I was, in fact, recalling an old nursery rhyme about the Dark Tower.
The Brigadier: Does it help?
The Second Doctor: Considerably more than you.
Tegan: You mean you're deliberately choosing to go on the run from your own people in a rackety old TARDIS?
The Fifth Doctor: Why not? After all, that's how it all started!
The Master: A cosmos without the Doctor scarcely bears thinking about.
The Master: I could easily kill you if I wanted to.
The Fifth Doctor: And not humiliate me first? Oh, that isn't your style at all!
The Fifth Doctor: Like Alice, I try to believe three impossible things before breakfast.
The Castellan: No! Not the mind probe!
Novelisation: Doctor Who - The Five Doctors by Terrance Dicks (ISBN 0 426 19510 8) first published by W H Allen in 1983.
Borusa is eventually freed from Rassilon's trap in the Doctor Who spin-off novels Blood Harvest and The Eight Doctors.
The scene where the Fourth Doctor and Romana are punting in a boat down a river before the Time Scoop kidnaps them is an excerpt from a scene in the unfinished and unaired Shada. In the original footage, when the Doctor loses the punt and overbalances on the boat he falls into the water, but this scene is altered to show the Time Scoop effect instead.
A brand-new TARDIS control console and interior set is created for this episode. It is last seen in Battlefield, Part One.
Sarah Jane Smith (Elisabeth Sladen) and K9 (voiced by John Leeson) appear next in the 2006 episode, School Reunion.
William Hartnell's appearance in this story is a clip from the ending of the final episode of The Dalek Invasion of Earth, where he is, ironically, saying goodbye to Susan. In a way, he does keep his promise, meeting up with her in the Death Zone.
Note the use of two classic Jon Pertwee clichés in this episode. First, the utterance of the deadly phrase, "No! Not the mind probe!" Then in Rassilon's tomb, the Third Doctor manages to unlock the tower's defences with a classic trick: reversing the polarity of the neutron flow.
Note the scene when Susan trips and sprains her ankle. On the DVD running commentary, writer Dicks says he included it for no other reason except entirely as an homage to Terry Nation, who almost always had his heroines sprain their ankles in scripts for the series. Susan sprained hers in the first episode of The Dalek Invasion of Earth.
DVD: Doctor Who: The Five Doctors Special Edition (BBCDVD 1006) released in November 1999. Released in U.S.A./Canada (Warner Home Video E1596) in September 2001. Doctor Who: The Five Doctors 25th Anniversary Edition(BBCDVD 1355), including both the special edition and the original broadcast edition, was released in October 2005. Released in U.S.A./Canada (Warner Home Video E2666) in September 2006.
Video: Doctor Who: The Five Doctors (BBCV 4311) released in September 1985. Released in U.S.A./Canada (CBS/FOX Video 3717) in March 1989. Re-released (BBCV 4387) in July 1990. A re-edited special edition (BBCV 5734), with extra and extended scenes, updated special effects and a new score, included (along with The King's Demons) in Doctor Who: The Five Doctors Special Edition/The King's Demons (BBCV 5737) released in November 1995. Released in U.S.A./Canada (Warner Home Video E1113) in February 1997.
The Time Lords offer the Master (now inhabiting the body of a Traken) a full regeneration cycle.
With Tom Baker unwilling to reprise his role as the Doctor, publicity shots of the five Doctors for this episode feature a wax model of the fourth Doctor!
At one point Colin Baker was to reprise his role as Commander Maxil from Arc of Infinity, but he declined. Given that Peter Davidson announced his intention to leave the series shortly after this episode was recorded, it seems likely that, if Baker had appeared, another actor would have been cast as the Sixth Doctor.
Continuity is maintained with the 1981 spin-off K9 and Company.
Rumours circulate of earlier drafts of the script featuring appearances by Autons, the different Doctors taking different paths through the Death Zone, and even one version where the villain turns out to be the first Doctor! The latter rumour was a script entitled 'The Six Doctors' in which the first Doctor would be revealed to be an android.
Richard Hurndall appears as the First Doctor in place of William Hartnell, who died in 1975. He advised later that the producer's had seen him in the Assassin episode of the BBC space opera Blake's 7, and thought that he looked like Hartnell's Doctor.
Tom Baker appears only in footage from the abandoned Shada due to his unwillingness to return to a show he still felt overpossessive about.
The series' most celebrated writer, Robert Holmes, was originally invited to pen this twentieth anniversary story. He declined, seeing it as a logistical nightmare, and Holmes' predecessor as story editor, Terrance Dicks, took up the challenge.
A 90-minute special.