The balcony has a solid low wall instead of open railing in this shot (and it only extends to the vertical post right). The stuntman will fall over the wall, which conceals the padded landing surface. Thanks to Shane Johnson.
When we first see Regina in Main Mission, her commlock photograph is actually of Simmonds (from Earthbound). When she runs into the Command Office, the commlock photograph has changed to her own. A publicity photo (shown above) shows the commlock photograph to be Helena. Thanks to Craig Rohloff.
In some scenes, Koenig's commlock buttons are wonky. This prop was in use until Collision Course
Regina doesn't wear standard blue Alphan pyjamas. They are a lighter silver-blue, with flared sleeves. The tunic looks like it is stitched together at the front, to stop it opening up. These pyjamas are also worn by Zova in The Exiles. Thanks to Richard Totis.
After Alan has placed Regina on the medical bed, Alan and Helena talk. Helena stands with the communications post behind her. In the reverse shot, we see another communications post beyond Alan. The shot is a cheat; the camera has barely moved, and it is the same communications post, and the same wall behind both actors. Barbara and Nick have merely swapped places so a new set wall didn't have to be constructed. Thanks to Craig Rohloff.
Regina's painting is by Keith Wilson. This is not the actual pre-production painting (which is shown here). The Regina painting is more cheerful: large sunflowers, fluffy white clouds and a red sun with a Van Gogh halo. The pre-production painting is darker and desolate.
The instrument that Regina uses to hit the mirror (and Mathias) comes from Helena's desk. Thanks to Chris Bentley's book The Vault (2022), we know the prop was used for a number of British science fiction movies as a Geiger counter.
It appears in the 1959 ITC series The Four Just Men episode "The Deadly Capsule" (aired ATV Midlands 19 November 1959), with it being used to find a missing radioactive capsule.
Here it is, held by John Saxon investigating a meteorite, in the 1965 black and white movie The Night Caller, which had several alternative titles including Night Caller from Outer Space. It was also in another black and white movie Invasion (1965), held by solders investigating the fiery crash-landing of the alien spaceship. Nick Tate's father, John Tate, appears in this film.
Peter Cushing holds it to examine the alien "silicates" in the 1966 colour film Island of Terror. Barry Gray did the musical effects.
The same instrument is used with another meteorite in the 1967 film They Came from Beyond Space, just before the scientists are taken over by the alien intelligence.
Regina dies in Alan's arms. Without checking, everyone assumes she is dead. This is drama, not reality. Helena should check her vital signs to see if she fainted, and attempt resuscitation. Until now they have assumed a mental problem after a thorough physical evaluation, so Helena should assume she can be revived. Thanks to John Day.
The abandoned Alpha has no power or atmosphere. Logically, there is no gravity either, and Koenig and Alan move in lunar gravity through the corridors.
The crashed Eagle doesn't have the dark panels on the sloping upper section (which may be windows or solar panels). They are the same grey-white as the rest of the pod. Thanks to Richard Totis.
The doppelganger spacesuits in the crashed Eagle have the names written inside the visors; the real Alphans have their names above the visors.
Helena gives Koenig the results of his autopsy. In the establishing shot, a Giano ashtray is seen on the left by the back wall. Later, the Giano has moved by the communications post and the Selene chair near it has moved.
The shot of the children shows the girl is much shorter. In the reverse shot of Koenig with the two children, both children seem to be roughly the same height, with the fair haired girl possibly even taller (depending on the effect of camera angle)
While the other "Earth" Alphans all look a little older and greyer, Victor Bergman seems to have got younger living on Earth. He's lost the grey in his hair. Thanks to Richard Totis.
When the two Helenas confront each other, we see a chess set in the foreground. This is the same chess set used in Dragon's Domain (as opposed to the set with real chess pieces seen in Black Sun). Presumably this is Koenig's personal set. Thanks to Richard Bendell
Earth Bergman says "We know that Regina died when she confronted herself in her mind. Our Helena died when she confronted herself in the flesh." Earth Helena says "My time here is finished. It's my own decision." Earth Helena dies in Koenig's arms, not when meeting Alpha Helena. Is it Helena's decision because she accepted her inevitable death? The logic and physical cause of one Alphan dying is fuzzy.
When they enter the space warp at the end, Bergman, Helena and Koenig are holding onto to Paul's desk. Sandra is in the foreground (on the computer side of Main Mission). Alan Harris is at the top of the steps on the window side. After the warp, we see the Alphans getting up from the floor. Bergman, Helena, Koenig and Sandra are now by the windows, Alan Harris is at Sandra's desk. Thanks to John Day.
In the epilogue, they see this nebula on the big screen. The shot is reused from the end of Black Sun.
Copyright Martin Willey. Thanks to Chris Moore.