Actually, it’s only four Doctors, and one of them is a substitute for the late William Hartnell, who had passed on several years before Doctor Who‘s 20th anniversary, when this 90-minute special episode was made.
Not only does this story involve getting all the Doctors together; the show’s creators seem bent on getting anybody who was involved in it during its run to date and was available to appear in it somewhere. There’s a lot activity being juggled between different groups of characters. I’m going to break my review up into sections.
But first, a short history of me and Doctor Who. In the early 1970s, our local PBS station began to air all the episodes of a given story on Sunday mornings. My little brother watched them, and was a much more keen viewer than I was.
The first episode I ever saw was of Jon Pertwee’s Doctor. I haven’t been able to identify which story that was; I believe the Doctor’s companion was Liz Shaw, and what I would later know to be UNIT was fighting off an alien invasion. Aside from that, I don’t recall much except that it was the first time I’d ever heard a British telephone ring. While I rather liked the Doctor’s sense of style, I didn’t take much interest in the story and only saw bits and pieces of subsequent stories until The Three Doctors. I started watching regularly during Tom Baker’s era and through Peter Davison’s, and those are the stories I still have the greatest affection for. (It helps that I’ve had a crush on Peter Davison since I was 17… going on 40 years now.)
This 20th anniversary show is one I remember watching when it first aired in 1983. We usually saw episodes of Doctor Who a year or two after they were shown in Britain, but this one actually aired in some parts of the US before its UK debut.
Since The Three Doctors, I’d been interested in the idea of Doctors meeting Doctors, the contrast of personalities even though they were the same person. It’s an idea I’m still partial to.
To include something of William Hartnell, the show begins with a clip of the First Doctor’s farewell speech to his granddaughter Susan, in which he promises that he’ll come back and they will see each other again.
The story proper opens with the current Doctor (Peter Davison, or Dr 5) and his two companions Turlough and Tegan* having a bit of a holiday in northern Wales, not far from Portmeirion. Dr 5 calls it the Eye of Orion and says it’s the most tranquil place in the universe.
This tranquility is not to last long. It wouldn’t be much of a show if it did.
Meanwhile, the group of Doctors’ companions and friends also escaped from Omega’s cave base are running across the desolate landscape with Brigadier Lethbridge-Stewart and Mr. Ollis the groundskeeper until they find Bessie where Dr 3 left her parked. They all pile in and the Brigadier announces that they’re going to UNIT HQ. “It’s nearer than you think.”
He intends spend his days writing a book on economics, and he and Mary are looking for just such a place as Lyng to live out their long-standing dream of retreating to the remote peace and quiet of a “genuine Elizabethan manor.”
At the end of the 
but during the activity that follows at UNIT, we’re given a very brief scene of them reappearing via that beam emitting from the so-called black hole and ending up unconscious in a quarry.
An old man in wellies and carrying a rifle–he’s the grounds-keeper–approaches to examine the box, which resembles a car battery, that’s attached to this rigging and anchoring it.
I don’t know why. It never ends well. When your husband’s been possessed by an evil ancestor he strongly resembles, it’s much more reasonable to leave your stately haunted home for a little while and wait to see if he has the willpower to reassert his own personality from a safe distance.”
everything he’s saying about their present state of timelessness, he tells her: