What's Wrong With... The Space Museum

Let's get the old joke out of the way first. You know the one. There are only three things wrong with this story, and they're Episodes 2, 3 and 4.
Like all the best jokes it's based on a kernel of truth. The Space Museum has a very good first episode, setting up a real mystery. Some incidental characters appear only briefly, so for the most part we concentrate on just the Doctor and his companions, trying to work out what is going on.
As soon as we start to get an idea about what this mystery is about, and the guest characters are properly introduced, it all goes to hell in a handcart.
Episode 1 is by no means perfect. There are some dodgy production values. Everything goes okay up until the time travellers leave the TARDIS. The planet set is far too small, with the background too close to the actors, meaning their shadows fall on what are supposed to be distant mountains. The walls of the museum are supposed to be multifaceted, as seen in the model shots, but viewed on modern TVs up close this has clearly been done with paint effects on flat surfaces when it comes to the studio set.
As they explore the museum interior, Vicki decides to ignore the Doctor's order not to touch anything, and we see her hand pass right through a piece of equipment. All the supposedly insubstantial items look transparent before people go to touch them. This was one of the problems with the Overlay technique. An object would be filmed by another camera elsewhere in the studio, brightly lit against a black background. That image would then be overlaid on top of the main image with the actors. We've seen it before in the series, such as when the TARDIS crew view the dead Farrow in Planet of Giants (where the secondary image is a blown up photograph), or in The Web Planet, when the Doctor and Ian view the pyramid. One of the reasons both actors were dressed in white costumes for that scene was because, had they been wearing dark colours, they would have become invisible against the black backdrop. 
As the overlaid item isn't actually present in the part of the studio where the actors are, you get line-up problems. William Hartnell ventures too close to the "not there" TARDIS and stands on top of it before reaching out. Much is made of the travellers being unable to touch objects, or leave footprints, yet they feel the floor under their feet, and lean against walls without falling through them.
The wallpaper, badly hung, behind the four exhibit cases also deserves a mention.
Fluff-wise, Hartnell struggles with the word "fluorescent".
You can tell that it's Barbara who's the history teacher, as Ian earlier mentions that they had been wearing 13th Century costumes, despite having just come from 1191.
There is also the discontinuity between the supposed size and labyrinthine nature of the museum and the relatively small building when shown as a model. Hard to see how anyone could get lost in it.
Some of the major problems with Episodes 2 to 4 might lie in a confusion about the tone of the story. We know that writer Glyn Jones, intended a lot more humour, which story editor Dennis Spooner cut out - surprising when you remember that he was the person who introduced more humour into the programme.
Jones called his villains Moroks, as in morons, and their leader is called Lobos, as in lobotomised. They were deliberately intended as being rather stupid, and everything they say and do tends to support this, yet the actors have been advised to play it straight. Had it been played more as Jones intended, this story might have had a better reputation.
After Episode 1 we know things are on a downward tread as we are introduced to Lobos, who is required to deliver some truly awful exposition. He's a Morok, talking to another Morok, yet he tells him things about Moroks that Moroks must surely already know. He talks about how this museum, where they both work, came into being, and even how long one of their years lasts. It doesn't matter how long a Xeron day is, a Morok year is still a Morok year.
Yes, this planet conforms to the Terry Nation school of planetary naming. It is an arid world, so just happens to have a name derived from the Greek word for dry - xiros.
If the planet is dry, then its inhabitants are most assuredly wet. They are all teenage boys, who dress in black skinny jeans and roll-neck sweaters, so look as if they should be at a youth club organising a skiffle concert rather than a revolution. If they are Mods then the Moroks must be Rockers, as they all sport enormous quiffs.
It is clear that lack of interest in this museum has been a problem for a long time, so you have to wonder why the Morok authorities have kept it going this long. We also have to question Lobos's belief that capturing the TARDIS crew will somehow revive its fortunes. Are the people of Morok really going to flock to Xeros to see a battered old Police Box, an old man, two schoolteachers and a schoolgirl?
In order to capture the travellers Lobos floods the museum with gas. This leads to Barbara being sidelined for almost an entire episode, struggling along a very short corridor with one of the Xeron youths. Ian, meanwhile, discovers that the Moroks aren't terribly good soldiers (unless they deliberately assign museum duties to their worst troops), and Vicki discovers that the Xerons aren't terribly bright revolutionaries. The Morok arsenal is protected by a computer sentinel, but she overcomes it in a matter of seconds. Seems the questions the machine asks don't actually have to be answered before moving on to the next one, and if you reprogram it to say you want the guns for a revolution then it is quite happy to oblige. The release of the guns leads to the terrible line "Have any arms fallen into Xeron hands?" from the Morok commander, who also struggles with the pronunciation of "guerrillas".
There's a lot of discussion about the missing button from Ian's blazer, with regards to them changing their possible fate, and yet no-one mentions the fact that Barbara's entire cardigan, which she was wearing in the display case, has been unravelled.
The revolution takes place, and the Moroks are defeated. No mention is made of possible reprisals from the Moroks, like reinvading the planet or nuking it from space. The Xerons then appear to empty this supposedly vast museum of its contents in a matter of minutes. The museum wall can be glimpsed through the TARDIS door in this scene.
We then get a very lame excuse for the mystery of Episode 1. It was just another stuck switch in the TARDIS, just like we had in the equally mundane conclusion to The Edge of Destruction.
At the end we have a lead-in to the next story, as a Dalek appears - reporting on the TARDIS's whereabouts. Bizarrely, all of the controls it's using are high up off the ground, rather than at plunger level.