The double-disc presentation of Inferno offers the by-now-standard wealth of extras, including commentary by Courtney, script editor Terrance Dicks, producer/director Barry Letts, and co-star John Levene (Sgt. Benton) and lengthy featurettes on the making of the story and the UNIT brigade during Pertwee's tenure (the latter featuring interviews with much of the supporting cast and crew). A short deleted scene from the episode (featuring Pertwee in a rare second turn as the voice of a radio announcer), a promo film for the BBC Visual Effects Department (which features clips from the Who stories Ambassadors of Death, Caves of Steel, and a missing episode from Doomwatch), and PDF files of the 1971 Doctor Who Annual and Radio Times round out the supplemental features. --Paul Gaita
One of the things for me which makes this interesting is not just the parallel world notion, which surprisingly has not been used too much, but the limits to that notion.
For instance the Doctor finds himself in an alternate universe which is slightly different from the one he begins from. Not only is it different but he, qua the Doctor is not in it, nor has he been. Also the concept that one parallel universe can be destroyed without destroying the others is a novel idea too.
This adventure has almost everything you could want to find in a show geared towards adults and young adults alike. The typical villain and mad scientist are found together in one mean man along with a devoted follower who is intelligent but too uncertain to question his authority. There are the Primords, who are the unfortunate by-products of the scientific process and then there are the populates of the alternative earth...
These neo-fascists clearly intended to resemble to gestapo/SS of the Third Reich and accurately portray an authoritarian regime. There is another aspect to this too which was controversial in England upon the show's broadcast and that was the appearance in uniform of Caroline Shaw. Adult viewing increased considerably.
The adventure is rather long, unecessarily so, and could have done with a better editing. Even so there is a good story here with much to consider for some time. The action scenes and outdoor shots as well as make up and costume have much to commend them. A very good concept which is pretty well executed. No pun intended.
The loss of the character Liz from the series was a hard blow. The Doctor clearly needed a companion who had at least half a brain but instead the third Doctor was portrayed as a well meaning but chauvinistic person rather than the enlightened man of reason he had set out being.
Hopefully this will make it ot DVD sooner rather than later.