On watch, Clea is fiddling with a control pad facing a screen. She turns around in her chair and the panel has vanished.
While Helena operates on a patient in a sterile room, Dr. Ed Spencer's nose is clearly visible above his sterile mask.
Toward the end of the episode, there are no signs that Tony had experienced any kind of head surgery.
The large block that Claire hits Yesta in the head with is very obviously foam.
Dorzak presses on Sahala's shoulders to knock her unconscious. When he picks her up, she very clearly and intentionally places her hand behind Dorzak's neck, as opposed to her hand falling slack.
In the closing credits, Richard LeParmentier is listed as playing Ed Malcolm when his character was actually Sam Malcolm.
On The Rules of Luton (1976), Maya had told Commander Koenig that she'd had a brother who had left Psychon with a thousand others. Eventually, the rest of Psychon's population also fled their doomed world. Dorzak claims that he and she are the only Psychons alive, giving evidence that they had all grouped together then entered the Croton system. Maya doesn't react to the apparent death of her brother. (Note: It's possible Dorzak's claim of the Crotons killing off the rest of Psychon's refugees was fabricated; other Psychon groups could've dispersed through the galaxies, Dorzak attempting to exacerbate Maya's hatred toward the Crotons).
While discussing Dorzak with Sahala, Alan states that he'd been aware that some of Maya's people had escaped Psychon before it blew up. It was obvious on The Metamorph (1976) (and specifically mentioned on The Rules of Luton (1976)) that when the Alphans had been on Psychon, Maya and her father were the last of their race residing on their planet. The rest of their people had evacuated.
How do the Alphans recognize a "Universal Plague Warning Signal"? As with most second season episodes, this ignores the fact that the Alphans are wandering into completely unfamiliar territory and know almost nothing about the peoples and cultures they encounter. (Note: Most likely Maya would be familiar with the plague signal due to her father's teachings, but neither Tony nor Helena ever mention this, even though it's the natural thing for them to do).
Maya (as Sahala) blows her cover when asking Dorzak how he was able to control Yesta's mind. He responds that "Sahala" already knows. Her question makes no sense as Maya already knew what the neurological jammer did and was present with Sahala when it was explained. (Note: Maya may have been fishing for a confession from Dorzak, not caring whether her cover was blown, simply searching for the truth).