The most noticeable difference with S1 is the increased tension between Blake and Avon. The antagonism was always there, but now it has reached a point of no return. From here on their road seems to lead inevitably to a showdown. [Leaving the viewer in delightful anticipation. :-)]
Here we have the first mentioning of Avon's survival instinct. [Indicating that this is the point where the writer / script editor has thought of attributing that trait to him. :-)] Blake does some nice fighting. Gan too makes himself useful, although that long jacket seems rather a hindrance. Avon shows he can run the fastest of them all, he's continually in front while they're fleeing through those bleak halls. [That fall isn't acted: the explosion went off at the wrong moment and blew Paul Darrow off his feet.] (Judith: for more interesting thoughts about that explosion, see the article on Oldbury Power Station in 'Zenith' magazine)
The end, with Blake ordering Avon back to his position, shows the new direction of the Series. Blake, always strong-willed and determined, is getting obsessed. Nothing and no-one will divert him from his chosen route. Makes for great drama.
Vila shows himself an unexpected strategist with his suggestion to fire a couple of seekers. For a man who shuns from violence he's strangely at home at the weapon's position. [Of course, just pressing a button is something else entirely than fighting your enemy hand-to-hand. :-)] And aren't they all accomplished technicians? Even Gan is able to accurately assess the damage in the sub-control rooms.
And there is that gorgeous scene with the live cable. Avon putting himself so casually in danger to rescue Blake had me gaping the first time I saw it. [But that's part of his delightful unpredictability. :-)] That explosive lying around for him to use seems a bit too much of a coincidence, but maybe time bombs are standard equipment in all of Liberator's sub-control rooms.
Again we are confronted with the females of the species being considered the most suitable for mind meddling. The Alta linked into the System are both women. [Yes, it's possible that there are men linked in too, but we don't see them.] All the guards appear to be men, as faceless (and inept) as the Federation variety. It's great to see those two grenade waving thugs being teleported back to throw them at the Alta.
Blake being rescued by the slave opening that hidden door is rather providential, but we can put it down to a streak of luck. The same goes for them all finding each other and then the ship back so easily - aren't they lucky that Liberator's parking space is right next to the detention block? :-) We get a last glimpse of the S1 Blake when he's hugging Jenna. :-)
"Go back to your position!" Schoolmaster Blake laying down the law on his most difficult pupil. This is the point where I started expecting Avon to shoot him. It is also the point that defines the changeover in Blake from determined to obsessed.
Avon deserves a kick (preferably with Jenna's sharpest heeled boots) for keeping his reassurance about Orac's prediction to himself. If he wanted to be asked he should have let them know that he could provide the answer. And he keeps ego-tripping, in warning the others about not going near the teleport without giving them the reason. [Well, maybe he considers them bright enough to work it out by themselves. :-)]
"I'll call you IF I need you!" And then he does. Oh, how he does!
The white hot guns: aren't there any protective gloves aboard?
Jenna cuddling up to Avon in that cell - their only companionable moment in the whole series. Well, people do strange things in the face of death. :-) Vila is poorly rewarded for his trouble to free them, but he gets the privilege of Avon apologising to him. [Must bring him into a very select company!]
Why build Spaceworld while the system has three planets? Were those made uninhabitable by the war or do the machines feel more at home in an artificial environment? :-) And what is cluttering up all Orac's circuits? [Or is it just trying to sound important?] At this stage they all seem rather in awe of Orac, even Avon.
At the end, when Zen puts the sister ship on the screen, why does none of them notice the background? It's exactly the same as in the earlier projection - all the reassurance they can want. :-)