A production error near the start of the episode meant that the "Voice of the Mysterons" (spoken by Donald Gray) was not lowered in pitch as much as normal (usually being very deep). It was easily recognisable as the voice of Gray, who also plays Colonel White.
Captain Blue and Captain Scarlet had functional hat communicators, so, despite what Captain Scarlet said, they could have alerted the observatory once the Mysteron Breck had revealed his plan.
Captain Scarlet kills the mysteronised Dr. Breck with a regular spectrum pistol, which goes against what we learned about electricity being the only thing that can kill a Mysteron agent.
In this episode the mini satellite is a claimed as being able to take 'the best close-ups of mars ever taken by man'. However in the first episode the entire story revolves around the fact that man has already landed on Mars and is exploring it. You would think that the photos they took would be better than the ones taken from Mars's moon Phobos.