- The Cameo: There's a cameo by the Fireflash, from the first episode. It consists entirely of Stock Footage from that episode, and seems to be mainly there for Padding. Oddly, it was featured in the preview.
- The Casino: where the episode starts and ends.
- Composite Character: - Braquasso is basically George Bracque and Pablo Picasso merged into a single artist. Both were hugely influential before World War One, though, as they developed Cubism pretty much single-handedly.
- Cross Dressing Voice: Ray Barrett is having the time of his life as the Duchess. Recording sessions for this episode were reportedly hilarious.
- Drill Tank: The Mole's third appearance.
- Machine Monotone: The Lift in the building of the buyer. With a twist, in that machines were totally not expected to be able to reciprocate pleasantries. In a sense it is still impressive when one considers the necessities for processing the vocal input.
- MacGuffin: the portrait of a Gazelle, that the bad guys want to get their hands on and which is the only object of value that the Dutchess has left after her disastrous evening at the Casino.
- Large Ham: The Duchess. Not only is her puppet one of the most charicatured in the series, Ray Barrett is having WAY too much fun doing her voice.
- Properly Paranoid: Lady Penelope worries that the Duchess' troubles aren't over yet when she departs for New York with her painting, and decides to keep a close eye on her. Her suspicions turn out to be correct.
- Tracking Device: Lady Penelope uses one to keep track of the dutchess during her trip to New York. This turns out to be a good thing since she is abducted.
Recap / Thunderbirds S 1 E 21 The Duchess Assignment
When the elderly Duchess of Royston loses everything at a casino in Monte Carlo, her friend Lady Penelope decides to help her. Enlisting Jeff Tracy's extensive contacts, Lady Penelope finds someone interested in purchasing the Duchess' last asset - Braquasso's "Portrait of a Gazelle". However, two crooks working for the crime syndicate responsible for swindling the Duchess at Monte Carlo kidnap the embattled aristocrat and make off with the painting, leaving her in a deserted house that is leaking gas. Can International Rescue save the Duchess before she falls victim to the ensuing inferno?