This episode was filmed simultaneously with A Matter of Balance (1976) (from August 5th to the 24th 1976), which is why Martin Landau, Catherine Schell, and Tony Anholt have limited screen time.
According to ITC's Season Two publicity, Moonbase Alpha was situated within the crater Plato on the north end of the face of the moon, located right above the enormous Mare Imbrium (which would make sense, considering the toll the base took when Nuclear Disposal Area 2 had detonated, placing the disposal areas not too far over the moon's horizon). In this episode, Maya (as the large bug-eyed creature) was found in the Copernicus depression. Apparently, she'd traversed across the entire expanse of the Mare Imbrium in about 45 minutes (she can only hold that form for an hour), which is quite a feat.
In the scene where Alan is thrown through the air in Medical, Nick Tate was prepared to perform the stunt himself but realized the ceiling of the set was too low for him to successfully land on the mat. Stuntman Tim Condren performed it for Tate, and due to attempting to avoid the low ceiling, missed the floor mat, knocking out his two front teeth and broke his collar bone.
SFX shots of the space warp (and the moon disappearing) were featured on Rush: Distant Early Warning (1984).
Terry Walsh is dubbed (one of the two Alphans attacked when Maya, as the "mossy" monster, initially breaks out of the Medical Center after knocking Helena unconscious).