Often heralded as the series' most memorable episode, because it featured live crocodiles in extensive footage filmed on a model set, a first for the AP Films team. During the episode's filming, publicity photos were taken of Lady Penelope (who did not appear in the episode) with a couple of the crocodiles, however, one of the crocodiles clamped its razor-sharp teeth around one of the puppet's legs and refused to let go swallowing the leg complete with pink sandal.
This episode and "The Man from MI.5" 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 this episode shows Thunderbird 2 lifting from the pod several minutes after landing. Normally, the pod is simply dropped on to the water.
The concept of genetic modifications to agriculture was already being worked on at the time of this short. It would become mainstream practice within a few decades.
The extensive swamp set was extremely well portrayed and a departure from most of the usual types of episode locations.
Both alligators and crocodiles (two similar but different species) regularly grow to more than 15 in length. The saltwater crocodile, native to Australia and Asia, has topped the record books at 23 feet.
But the perspective shots here would indicate the modified critters were considerably larger than that.