An experimental growth hormone is accidentally released into the South American jungle. This causes the local alligator population to grow to ten times normal size. A house in the jungle is besieged by the vast monsters and it's up to International Rescue to save the people within!
- Artistic License – Biology: The alligators were played by crocodiles.
- Perhaps they were illegally brought in and released into the wild as an invasive species. A problem with snakes in Real Life.
- Badass in Distress: Acting as live bait to draw the last alligator away from the house, Alan manages to knock himself out on a tree. Gordon must get him to safety before the alligator reaches him.
- Dramatic Thunder: A convenient storm means the scientists all have to spend the night in the remote house...
- Draw Aggro: Alan lures an alligator away from the house, by riding his hover bike nearby, while grinning from ear to ear (as much as his puppet face allows). Unfortunately, he is looking behind him at the alligator, and crashes his bike.Alan: Here boy! Come and get me.
- Hoist by His Own Petard: Culp, the bad guy who released the growth hormone into the swamp, gets eaten by a giant gator himself.
- Leeroy Jenkins: Alan, who rushes in to lure the last alligator away from the house. It works, but he nearly gets killed.
- No Animals Were Harmed: Unfortunately not the case, despite the production team's best efforts. Some members of the production team refused to cooperate and there was a representative from the RSPCA on set to ensure a minimalization of animal abuse. The production team used electric shocks to get the "gators" (actually juvenile crocodiles) to go where they wanted and the crew recalled that when the RSPCA man found out, he pointed out that the crocs wouldn't even feel the 20V they were using and recommended upping it to 60V! Still, some of the young crocs sustained minor injuries and one unfortunately died of hypothermia overnight. They were also rather aggressive with handlers and one of them ate the legs off a Lady Penelope puppet.
- In-Universe, the Tracys try this approach as well, luring the alligators away from the house and successfully tranquilizing all three of them. However, with Alan knocked out luring the third alligator away and Gordon keeping watch in Thunderbird 4, Virgil is forced to kill the last alligator with a missile as he has no-one to operate Thunderbird 2's tranquilizers.
- Old Retainer: Mrs. Files, who serves as a bit of a Red Herring in the beginning as she looks like she might be a bad guy. She isn't.
- Ridiculously Cute Critter: The pygmy alligator that Alan gets for his birthday.
- Reluctant Mad Scientist: Orchard, who would rather not see his growth formula fall into the wrong hands. Better pay attention to that unsavory boatman you've got lurking around the lab...
- Secret Underground Passage: Mrs. Files mentions the previous owner of the house, Lopez, had one of these installed, but never told her its location. This looks like it's going to be vital to the rescue, but the passage only ends up saving Culp's life (at first), who knew about the tunnel since he was a close associate of Lopez.
- Screams Like a Little Girl: Culp, on seeing a giant alligator advancing towards his boat.
- Slurpasaur: Little crocodiles play giant alligators alongside miniatures of the characters, but since working around the limitations of models and miniatures was what AP Filmsnote did, it actually worked fairly well. (At least, according to one story, once the stagehands figured out that the alligators needed to be goaded with 60-volt prods and not just 12.) Have a look.
- Stupid Evil: Pretty much every decision Culp makes throughout the episode is ill-advised. When he steals the theromene, his clumsiness knocks it down the drain and he thoughtlessly washes it down without considering that it could end up in the river. Afterwards, rather than conceal the vial he stole and use the passage to escape, he instead tries forcing Scott to help him escape at gunpoint by threatening to pour even more theromene into the river, a threat that would clearly make his situation worse. And while this does get him the assistance he wants, it proves to be not enough, as Virgil is too late to follow Gordon's warning and Culp is thrown overboard by the final alligator and presumably devoured. His decision to steal an experimental hormone on his own and with no backup from the single area that it can be found on the planet also wasn't very smart, even if he knew the area.
- The Tag: Tintin presents Alan with a pygmy alligator for his birthday.
- What Happened to the Mouse?: We never see Alan's pygmy "alligator" (really a crocodile) again after this episode.
- Whip Pan: On receiving the emergency call, John in the space station says "Giant Alligators?!". The camera then whips to Scott at the base saying the same thing.
