There is something on the floor by Kano's feet. It looks like a cigarette stub. Thanks to Richard Totis.
As the camera tracks down the corridor towards Hydroponics Unit 2, we pass a communications post. On the sign pointing left it says "Hydroponics Unit 2", but the actual Hydroponics Unit 2 is visible beyond. Later, when the camera tracks out of the Unit past the same communications post, the opposite signs can be seen. Seen from this side, "Hydroponics Unit 2" points to the other direction (still not in the direction we came from).
As the camera tracks through the door of Hydroponics, the shadow of the cameraman can be seen on the door frame (or is it Mateo's ghost?)
As the camera tracks towards the window, we can see a white reflection moving over the shoulder of the man on the left. This is probably the camera crew.
Compare the title shot of this episode, with the POV shot of space when Koenig looks out the windows at the start of Space Brain, the opening shot of The Infernal Machine, and the shot of the Moon in deep space immediately after the flashback sequence in Dragon's Domain.
Helena's commlock prop is different when she uses it. When she sees the ghost in Medical, her commlock has all 9 keypad buttons with numbers. In the next scene as she explains to Koenig, the prop on her belt is missing the top left button and none of them have numbers.
Mateo rises from the bed in Medical in his pyjamas and Helena gives him his uniform. He then mimes putting on his trousers, or maybe taking off his pyjama pants; whichever, he does not do both, take off his pyjama pants and put on his trousers. Perhaps he was not wearing anything when he talks to Helena. He doesn't put on socks or shoes either. Thanks to Gordon.
One wall of the Hydroponics Unit is a large window to the lunar surface (probably inspired by the film Silent Running which featured a spaceship with domes full of plants). The painted backdrop of the lunar surface is barely glimpsed, but this shot shows a painted antenna.
There are many reflections of lights and indistinct shapes of camera equipment in the glass, but this shot reveals the ghostly head of a man in glasses, top left.
Koenig orders "restrict access for everyone except Doctor Russell, Professor Bergman, Doctor Mathias and myself." Yet a guard (Tony Allan) is present at the door.
Bergman's forcefield terminals are actually National PB3 folding flash guns with a metal spike where the bulb should be screwed in. The same type of flash guns (possibly these props) were used as hand-held scanners in Year 2.
In these publicity photos, Sarah Bullen starts laughing. Zienia Merton turns smiling to her, two others are laughing behind her, while Barry Morse gives her a stern look.
Who's at the recital? There are 34 people (including Jim Sullivan, the musician). Note that almost everyone here also appears in the corridor evacuation scene later.
The call sheet (for 21st November 1974) lists 18 named artistes, plus "7 Men, 7 Women" which is 32 total, but there are 2 others also on-screen.
Actors who were in the scene but not positively identified above: Laurie Davis (Davis is also in the Main Mission scenes)
Copyright Martin Willey.