The relationship between Susan and David begins to deepen. In part this is due to their shared experiences – in this episode, the pair (in hiding) hear the Daleks exterminate a poor unfortunate.  “You killed my wife and my brothers, now you want to kill me, argh, get away from me! No, no, no…argh!”  Ford’s reaction sells the horror of the moment more powerfully than if we’d actually seen the man killed.  Following this disturbing moment, Susan wishes that they could simply leave.

SUSAN: If only we could go to the ship and get away from here.
DAVID CAMPBELL: Well, I couldn’t go anyway.
SUSAN: Oh, David, David! Perhaps you could! I…I..could ask Grandfather and I’m sure he’d let you come. Oh, we could go to place where they’d never even heard of Daleks.
DAVID CAMPBELL: And what happens if there’s something unpleasant in the new place?
SUSAN: We move on somewhere.
DAVID CAMPBELL: No Susan, that’s not for me.
SUSAN: Why not?
DAVID CAMPBELL: Look, things aren’t made better by running away.
SUSAN: Well its suicide to stay here.
DAVID CAMPBELL: This is my planet! I just can’t run off and see what it’s like i
SUSAN: I never felt that there was any time or place that I belonged to. I’ve never had any real identity.

The Doctor of S1 would have agreed with her and no doubt would have been just as keen to hot-foot it out of there, but Susan should know by now that the new, improved S2 Doctor is not going to leave until the Daleks are defeated.  It’s also notable that in the last few episodes Susan has begun to express a little dissatisfaction with life aboard the TARDIS.  This is something we’ll see repeated over the years and it usually happens just before a companion is due to leave.  Anytime a companion starts to complain more than they normally do (another obvious example is Victoria in Fury from the Deep) you know they’re heading for the exit door.

The various team-ups that will endure over the next few episodes are now falling into place.  Barbara and the balaclava-loving Jenny begin to head for the mines in Bedfordshire.  Coincidentally, Ian is trapped on the Daleks’ saucer which is also heading for the mines in Bedfordshire.  Also hiding on the saucer is Larry (Graham Rigby) who wants to get to the mines in order to find his brother.  Larry is one of those characters who appear again and again in Doctor Who – they exist partly to line feed other characters (in this case Ian) and once their usefulness comes to an end they tend to be killed off.  The Doctor is reunited with Susan and together with David they decide to head … north (I’ve got a feeling they’ll end up at the mines at Bedfordshire, don’t you?)

Day of Reckoning is notable for a major location sequence in which Barbara, Jenny and the doomed Dortmunn flee from the Daleks whilst passing as many well-known London locations as they can fit in.  Accompanied by Francis Chagrin’s unusual percussion-based incidental music it’s an iconic few minutes – not least for the Daleks waving their suckers in a Nazi-salute style.

Hartnell doesn’t have a great deal to do in this episode, which is just as well as he was injured during rehearsals (as he was being carried down the Dalek saucer’s ramp he was dropped on the floor).  This could have been a lot more serious – Hartnell was temporarily paralyzed – but he recovered well enough to record the episode in the evening.  But it was recommended that he spend a few subsequent days recovering in bed, so he was hastily written out of the following episode (although luckily he wasn’t a major figure in that one either).