Character mistake: When Gordon and Scott are playing chess at Tracy Island towards the end of the episode, the chess board is oriented incorrectly, as there is a white square in the bottom-left corner.
Terror in New York City - S1-E4
Character mistake: When Jeff is on the phone to Washington, thanking them for arranging the Sentinel to pick up Thunderbird 4 and take it to New York, the man in Washington replies, "That's the least we can do, Mr Tracy." So at least one person knows that Jeff is involved with International Rescue. This betrays the secrecy of the organisation that Jeff himself demands.
Terror in New York City - S1-E4
Character mistake: Inside the Mobile Radio Control Police Van, there is an "Ultra Short Wave" device that is labelled "Ulta Short Wave."
Character mistake: Tim Casey is a Colonel, but Scott refers to him as a General in one scene.
Character mistake: When Lady Penelope visits the psychiatrist in his office, she addresses him as "Mr. Korda" instead of "Doctor".
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.
Character mistake: When Brains is playing chess with Braman at the end of the episode, the positioning of the chess board is incorrect, as for both players there is a white square in the bottom left corner.
Character mistake: Scott flew to Ireland to look for the missing Fireflash airliner, but when Jeff asks where Scott is, Virgil replies, "His take-off from England was delayed for some reason."
Character mistake: After the first Fireflash crash, search and rescue tasks are unable to find the wreckage, and John in Thunderbird 5 comments that its position was way off what was reported. However, he never bothers to relay this vital information to the London airport overseeing the rescue effort, and IR never bothers to attempt a rescue of a passenger jet filled with civilians, despite showing on the second crash that they were completely capable to saving them. It's then stated that the crash had no survivors, which the viewer has to lay at IR's feet. Even if they were busy with another rescue at the time, notifying the conventional rescue effort of Fireflash's real position could have saved many lives and given the investigation more evidence to find the problem.
Character mistake: The situation in this episode is that a clerk, Lambert, is trapped inside a bank vault that is having the air removed. When IR arrives they focus all of their efforts on forcing a man-sized entrance before the air runs out, but don't consider first making a small hole to allow air in, thus giving them plenty of time to create an entrance afterwards.
The Duchess Assignment - S1-E21
Character mistake: When the croupier at the Duchess' table calls out the phrase "Rien ne va plus" (French for "no more bets"), he pronounces "Rien" incorrectly - he pronounces it "RINE ne va plus" instead of "REE-en ne va plus".
Character mistake: The end of this episode concerns IR chasing down a copy of the photos the Hood taken of the Thunderbird vehicles. However, they show no concern for being photographed in person, as they're lounging around in casual clothes in the end, on an active film set with cameras everywhere, and no camera detector on their persons.
