Revealing mistake: When the dummy plane is shot out of the sky by the fighter pilot, a piece of the plane shoots off into the top left of the screen and bounces off the sky background. (00:23:05)
Continuity mistake: When Scott is in the cockpit of the Mole, he has two blue tubes in the holsters of his belt. But when he is cutting through the fire doors, the tubes have changed to one blue and one yellow.
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: 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)
Visible crew/equipment: When Tin-Tin responds to news of Scott's disappearance, a floor puppeteer's hand (with dirty fingernails) can be seen at the bottom of the screen lifting Tin-Tin from her seat.
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).
Continuity mistake: While Gordon Tracey searches for the crashed Fireflash wreckage on the seabed, the parting in his hair keeps changing sides from shot to shot.
Continuity mistake: When the Hood is taking photographs of Thunderbird 1 at London Airport, one of the photos shows the letter "T" of Thunderbird painted on the red nose cone. All other shots of the craft show the nose cone free of markings.
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.
Attack of the Alligators - S1-E23
Visible crew/equipment: A film camera and its camera operator can be seen reflected in the glass during a shot of Mrs. Files at the window of Orchard's house in the opening sequence.
Continuity mistake: When the door of Pod 1 opens after Jeff realises there is a saboteur on board, we see three vehicles in the pod and beside the Monobrake there is a red unit which has a windshield on it. However, when we see Chip appearing in the next shot, the windshield has gone.
Deliberate mistake: When one of the yellow fire trucks moves away from the burning Thompson Tower, the back of the truck is set alight by the flames.
The Perils of Penelope - S1-E3
Continuity mistake: When Lady Penelope is in her bed in the monorail, she is wearing a pink night dress, but when Penelope awakens to find an intruder outside her room, she is now wearing a blue dress.
Continuity mistake: When Scott and Virgil leave the Mole on their hoverbikes, their uniform sashes are over the wrong shoulder.
Continuity mistake: When the Carter family are driving in their car to the Thompson Tower, Joe is driving and Blanche and Tommy are sitting in the back. But when the car stops at the ticket machine, Blanche and Tommy have disappeared.
Character mistake: During the television report about the Sun Probe, a diagram shows the solarnauts' control cabin within the Probe Module. But we later see that the control cabin is within the body of the Probe Rocket when the Module is fired into the solar prominence.
Continuity mistake: When Virgil is seating at the cockpit during the launch sequence of Thunderbird 2, he is wearing the clothes he wears on Tracy Island and his International Rescue costume appears. But when Alan comes down the lift, Virgil has suddenly changed into his IR costume.
Continuity mistake: When the Hood is taking photographs inside Thunderbird 1, we see a close-up of his hat. On the hat, it says "Airport Police" on the lens, but when we see a full view of the Hood, the words are no longer visible.
Terror in New York City - S1-E4
Continuity mistake: During the missile attack on Thunderbird 2, Virgil says "Missiles!" in the cockpit and his forehead can be seen to have sweat on it, but after a quick shot of the missiles flying through the air, we cut to Virgil again and the sweat has disappeared.
Revealing mistake: When Thunderbird 2 returns to its hangar at Tracy Island, smoke can be seen flowing back down into units inside the hangar, revealing that this is simply reversed footage of the regular Thunderbird 2 launch sequence.