This is the only episode where Virgil is seen on board Thunderbird 3, and Gordon on Thunderbird 5.
This is the only episode where Virgil does not take off in Thunderbird 2 immediately after it is raised on the platform. (He waits until after Thunderbird 3 takes off in this case).
This is the only episode in which both Thunderbirds 2 and 3 are shown returning to base.
This episode takes the notion of 'pirate radio' into the space age future. At the time, pirate stations operated from ships anchored just outside the legal limit of a nation's shoreline. Almost 50 years or so later, the concept of actual satellite radio, available to subscribers, would enter the entertainment market in 2002.
One of the few missions on which Thunderbird 1 is not used.