Factual error: An edition of the 'Melbourne Herald' newspaper can be seen in this episode, and appears to be dated Friday, December 24, 1964. Yet 'Thunderbirds' is supposed to be set in the 21st Century (2026 or 2065, depending on who you believe). This date is also seen on newspapers which appear in the episodes 'Edge of Impact', 'The Impostors' and 'Cry Wolf'. Also, to compound the error, December 24th, 1964 was actually a Thursday, not a Friday.
Plot hole: The Mighty Atom is only supposed to take pictures of human faces yet we see it taking photos of the machinery in the Saharan Plant when no one is in the room.
Factual error: The reactor controllers in both plants, and Brains, claim that cutting off the seawater intake would resolve the runaway reactor, and help bring it under control. In fact the opposite is the case - the plant's purpose is to purify and desalinate seawater by boiling, so processing more of it would soak up the excess heat the reaction is producing. Cutting off the intake would prevent adequate cooling, allowing the heat to build up and damage the plant further. We know the seawater isn't somehow used for fuel, because we see Scott and Virgil operating fuel rods in the reactor.
Other mistake: When Virgil says "That's better" when he and Scott are pushing the reactor rods back in place, his mouth does not move.
Audio problem: When the Reactor Station Guard catches The Hood taking pictures, he can already be heard blowing his whistle before he finishes saying "Hey, what are you doing?"
Continuity mistake: When Professor Holden is demonstrating The Mighty Atom to the other professors, the position of the device on his hand changes between shots.
Continuity mistake: When we see the Hood destroying The Mighty Atom at the end of the episode, the control box is much closer to the device than it was in the previous shot.
Audio problem: When the second reporter says to the first reporter, "Panic's over then. Did you hear the cloud got blown away?", it is said by David Graham instead of Matt Zimmerman.
Continuity mistake: The Mighty Atom is brown but changes to gray in closeups.
Other mistake: When Lady Penelope is relaxing with Jeff and the other members of International Rescue on Tracy Island, you can see in the lounge the pictures of the Tracy sons are in "Operation Cover-Up" mode, even though there are no other visitors on the island.