The music used at the end of part one of this episode was also used in Codename Europha of Scarlet when Carney was being Mystronised and used again in The ghosts of space and Space city special.

Just how often does Fireball call Space City with routine homing checks?
The bomb went off shortly after Steve signed off. By the time he made it down to the space gyro station, Commander Zero was fretting that Steve had not made his next regular check.
BTW, if the bomb was set off by the neutronie (sp?) waves of a radio transmission, as Steve indicates later in the show, then why hadn't the bomb gone off long since? Surely that wasn't the first time they'd made a transmission since the beginning of the patrol.

They also indicated that the reason the people of Electra (Electrons? Oh, brother!) had not reached Earth was because their gamma-powered ships needed frequent recharging. They apparently were damaging Earth ships so that they could capture and use them. This being the case, how did they manage to get to Earth and plant bombs in Space City?

Why did they suddenly lose their gravity on the ship, right before they all floated out away to the light? (And without bothering to take oxygen pills! Those gamma rays are really something!)

What is with these people traveling out in space all alone? First the Master Astronaut, then Commander Zero? The most basic safety measures would insist on taking at least two people, probably more.

That Electron leader really is superior! Putting Humpty Dumpty (sorry, Robert) back together again in under two minutes time!