Plot hole: In order to build up suspense, Virgil and Brains stand on the Crab Logger as its dangerous fuel is pumped out, despite the fact that it is hanging on the edge of a precipice. In fact they could have left as soon as they had plumbed in the pipes to empty the fuel tanks - the whole procedure is controlled by Scott in Thunderbird 1 and they make absolutely no contribution to the operation at all. They do not need to disconnect the pipes; they are left behind and dropped from Thunderbird 1 as planned. They just stand there chatting about how much danger they are in until jumping clear at the very last second. Silly buggers.
Continuity mistake: When The Hood drives his van off the broken bridge whilst escaping the police, watch carefully; the van bounces off the rocks on the other side and starts to fall roof-first into the river below. However, when it cuts to the van falling into the water it falls in upright. (00:42:00)
Continuity mistake: When Thunderbird 2 leaves the hangar on Tracy Island, it appears that Pod 3 has been selected (Pod 2 is visible to the right of Thunderbird 2), yet when Virgil and Brains arrive at Mount Arkan, the Transmitter Truck emerges from Pod 6. (The same continuity error also occurs in the episodes 'Vault of Death', 'Move - And You're Dead', 'Martian Invasion', 'The Perils Of Penelope' and 'Day of Disaster', probably due to the same footage being re-used for those episodes).
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.
Continuity mistake: Near the end of the episode, Jeff activates Operation Cover-Up to change the wall-mounted pictures of the International Rescue members from the usual pictures of them in their uniforms to ones of them in casual clothing before a doctor who has just examined Kyrano enters the room. However, while he and Jeff are talking, a couple of shots of Scott and Gordon contain enough of the pictures to show that they have reverted back the ones of them in uniform. (00:48:35)
Revealing mistake: Near the end of the episode, Thunderbird 2 lands and reverses into its hangar. During this bit, if you look carefully you can see white smoke near the boiler on the far side of the hangar, only this smoke is apparently being sucked into it. This is the usual footage of Thunderbird 2 exiting the hangar played in reverse. (00:42:05)