Lady Penelope's yacht FAB2's only appearance in the series.
Hydrofoil boats were being used in Europe at the time of this episode. They were quite popular as passenger ferries between Great Britain and European ports. The patrol boat seen here is modeled after the new aquatic mode of transport.
Espionage themes were extremely popular in film and TV projects during the 60's. MI5, the same British security agency that employed James Bond, is seen here working with Lady Penelope.
This episodes, and "Attack of the Alligators!", feature the full Thunderbird 4 launch sequence shown from inside Pod 4. In other episodes featuring Thunderbird 4, we have only seen Thunderbird 4 emerging down the ramp from outside the pod door. "The Man from MI.5" is the only episode in which Thunderbird 2 gently rests the pod on the surface of the water and then rises clear of the pod with lifting jets, whereas "Attack of the Alligators" shows Thunderbird 2 lifting from the pod several minutes after landing. Normally, the pod is simply dropped on to the water.
Update: Though not mentioned in the episode, it is quite possible that IR was concerned that the sound of dropping the pod into the water (as is normal) might have alerted the submarine to their presence. This also has to be balanced with the noise generated when Thunderbird 4 enters the water - though the noise generated by that operation would be considerably less than the noise generated by dropping the pod.
Update: Though not mentioned in the episode, it is quite possible that IR was concerned that the sound of dropping the pod into the water (as is normal) might have alerted the submarine to their presence. This also has to be balanced with the noise generated when Thunderbird 4 enters the water - though the noise generated by that operation would be considerably less than the noise generated by dropping the pod.
Just as the names 'Johnson' and 'Peterson' are derived from 'Son of John' and 'Son of Peter', respectively, the intent of using 'Bondson' as the name of the agent from MI 5 is more than likely intended to indicate he is the Son of Bond (or some direct descendant of Bond, perhaps the grandson - considering the intended date of the series).