The Duchess Assignment - S1-E21
Continuity mistake: After the Duchess has been rescued by "those romantic young men from International Rescue," when the Duchess removes the canvas from her umbrella, in the closeup (with human hands) she's wearing a pink button-down, but in all other shots there are no buttons whatsoever. (00:45:20)
The Duchess Assignment - S1-E21
Other mistake: When the WAT Wombat lands on the runway, the jetex attached to the underside can be seen falling off.
The Duchess Assignment - S1-E21
Continuity mistake: The pod chosen for Thunderbird 2 in order to rescue the Duchess from the burning house is Pod 3, but if you look carefully when the Mole is coming out of the pod, you can see "Thunderbird 2 Pod 4".
The Duchess Assignment - S1-E21
Audio problem: In the opening scene at the casino, the rogue croupier at the Duchess' table is voiced by Matt Zimmerman, but when the same croupier calls out "18 red", he has a completely different voice provided by Peter Dyneley.
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".