Two weeks after the rescue of Tyrannosaurus rex, the time has come for the park to stock up their newly designed Carboniferous themed bio-dome building with animals from the Carboniferous period. Naturally, this means capturing a decent number of prehistoric invertebrates, much to Leon's trepidation. But over the course of the shenanigans that ensue, it soon becomes clear that unnerving invertebrates could well be the least of the rescue team's problems. Meanwhile, back at the park, life continues to unfold happily, but not without several new characters and potential big plans being brought into the fold.
- Accidental Misnaming: Drew ends up accidentally referring to Eshe as Esme over the course of telling Adrian and Leon why Jack and Alice aren't accompanying them on this episode's mission.
- Adaptational Name Change: The newly discovered Carboniferous spider species were named 'mesothelus' in Prehistoric Earth for the sake of simplicity and synergy with the Walking with Monsters it was tying in with. Here, the spiders are instead given the genus name megalorachne.
- Agony of the Feet: Leon gets his right ankle bitten by a female crassigyrinus.
- Amphibian Assault: The proterogyrinus and pholidogaster actively attempt to charge at the rescue team while snapping their jaws like crocodilians over the course of their rescues. The crassigyrinus also attempt to swarm Leon and Drew while in the same pool as them (with one of them even managing to bite Leon's ankle beforehand).
- Amphibian at Large: The eucritta and phlegethontia are the only rescued prehistoric amphibians featured that aren't large enough to qualify as this trope.
- Ascended Extra: In Prehistoric Earth, researcher Kaisumi Ishiara only appeared for a single brief scene in which she never even got any lines. Here, she serves a major role in providing assistance for Khatin, Will, and Matt from the moment she's first introduced, and gets multiple lines of dialogue to boot.
- Battle Amongst the Flames: While not quite fully a battle, Drew ends up undergoing quite a struggle against Melancholia the female arthropleura when he works to rescue her while in a clearing surrounded by thick flames.
- Big Creepy-Crawlies: Considering the time period, these are naturally amongst the animals rescued. Subverted though in regards to the arthropleura, which end up getting the creep factor removed by their size instead of enhanced by it.
- Big Damn Heroes: Arlo is able to be used as an improvised tow-truck in time to get Leon and Adrian back to the safety of the park in the climax in time to avoid getting roasted to death in a Carboniferous period swamp fire.
- Birds of a Feather: Jack and Yolanda are revealed in the narration to have become friends, and they do have relatively similar personalities and senses of humor.
- Boys Like Creepy Critters: Jack and Nikolai are revealed to have both immensely enjoyed catching and releasing insects when they were younger.
- Canon Immigrant: Much like in Prehistoric Earth, the 'mesothelae' spiders (named megalorachne in this continuity) are introduced in this chapter as an undiscovered species.
- Continuity Nod: After Eshe the American cheetah is successfully integrated with others of her kind at the park, Yolanda mentions how much of a relief it is for her integration attempt to be successful after the less fortunate results of Arlo's attempt at doing the same back in Red in Tooth and Claw.
- Speaking of Arlo, he is finally confirmed to have indeed been subject to training to serve as a makeshift tow truck for transports of some of the larger animals in need of veterinary care, and shown to put his training in action for the sake of getting Leon and Adrian safely extracted from the Carboniferous period when their jeep starts stalling at an incredibly inappropriate time.
- Creepy Centipedes: Subverted with Felix and Melancholia the arthropleura. While they both manage to briefly startle the rescue team members who encounter them in their introductory scenes, they both prove Gentle Giant type creatures later on. In fact, their large size arguably robs them of their creep factor instead of enhancing it.
- Death from Above: The unfortunate fate that befalls a hylonomus as a result of Neith the megalorachne abruptly lunging out of her burrow and landing upon it.
- Drama-Preserving Handicap: For unexplained reasons, Drew's portal starts malfunctioning after he's rescued Felix and the proterogyrinus float, which convinces him to have Leon and Adrian (whose portals appear to still be functioning perfectly fine) to use their portals sparingly and only on animals that can't be safely kept within any of the smaller pet carriers and 'bug cages' they've brought along for the trip.
- Dreadful Dragonfly: Largely averted with the meganeura; for despite their size, they don't cause any trouble or harm outside of proving difficult to capture.
- Fantastic Fauna Counterpart: Most of the temnospondyls and other large carnivorous amphibians behave remarkably similarly to alligators and other crocodilians.
- Gentle Giant: Despite giving the rescue team a good startling in their first appearances, Felix and Melancholia the arthropleura prove quite friendly and affable arthropods once they've calmed down.
- Giant Flyer: The meganeura.
- Giant Spider: A single female megalorachne proves at least the size of Leon's head.
- The Great Fire: The climax of the mission involves the rescue team and the animals they've rescued having to escape from a vicious lightning strike induced swamp fire.
- Hidden Depths: Jack and Nikolai manage to start bonding at the end of this chapter, showing off their own mutual cases of this in the process.
- Moment Killer: Duke manages to bring a moment of Ship Tease between Jack and Colette to a halt by letting out an amused squawk as he's watching them in the midst of it.
- My Car Hates Me: Swamp water that ends up somehow getting into the engine of the rescue team's jeep offscreen causes the jeep to stall and become unable to properly start right when Leon and Adrian need to get it moving so they can get themselves and their collection of newly captured small Carboniferous animals through the portal in time to avoid getting roasted to death in a wildfire.
- Mythology Gag: The events of this episode bare some heavy similarities to the Bug House episode of the original Prehistoric Park series.
- Never Smile at a Crocodile: Many of the larger amphibian species rescued in this episode act a lot like crocodiles, with some of them proving a bit of a handful to capture.
- Opposites Theme Naming: A variant of this is invoked in the naming of the two arthropleura, with Felix being named after the Latin word for luck and Melancholia being named for a type of feeling one could potentially feel when at a particularly unlucky point in his or her life.
- Outrun the Fireball: Drew, Leon, and Adrian find themselves having to hurriedly flee from a swiftly approaching wildfire.
- Red and Black and Evil All Over: While not evil, the megalorachne are certainly portrayed as plenty unnerving (especially for apparent arachnophobe Leon), and they have black bodies with red pincers. Similarly, the pulmonoscorpius have black exoskeletons with red stripes on their claws and red tipped tails.
- Religious and Mythological Theme Naming: One of the female pulmonoscorpius is named Selqet (after the Egyptian scorpion goddess). Similarly, one of the female megalorachne is named Neith (after the Egyptian goddess of the hunt).
- Scary Scorpions: Subverted with the pulmonoscorpius. While given seemingly unnerving descriptions and played for suspense in the very first scene featuring them, they are ultimately portrayed as no more dangerous than any other modern species of scorpion (and Drew even manages to get stung multiple times by a couple of them without getting envenomated or seriously ill).
- Shout-Out: Several of the large amphibians are named after characters from Amphibia.
- More specifically, two of the proterogyrinus are named after General Yunnan and King Andrias, whereas three of the female crassigyrinus are named Sasha, Anne, and Marcy (with Sasha, appropriately enough, being the one who ends up biting Leon's ankle).
- Snakes Are Sinister: While not truly snakes, this trope is nonetheless averted with the phlegethontia.
- Spiders Are Scary: As unnerved as Leon is by multiple species of invertebrate, spiders are the only one that he's legitimately terrified of. Unfortunately for him, he, Drew, and Adrian manage the hard way to discover a previously unknown species of prehistoric spider.
- Swamps Are Evil: Downplayed, as the Carboniferous swamp environment the gang visits during the mission isn't necessarily evil or any more dangerous than any modern day swamp. Nonetheless, several of the animals that do live in this swamp during this time period do prove fairly dangerous in their own right.
- Took a Level in Badass: Leon shows yet more signs of slowly achieving this by managing to both successfully capture four pulmonoscorpius by himself without using his noise broadcasting device and successfully goad a float of pholidogaster into charging through the portal while at a point in which he's being forced to use a makeshift crutch to walk after having dealt a savage injury on his ankle by a crassigyrinus.
- We ARE Struggling Together: Despite all of them being mutually in danger from the approaching wild fire, the entirety of the pholidogaster float is visibly fighting against each other for the right to enter the nearby lake for safety. Fortunately for them, this puts them in ideal circumstances for Leon to goad them into charging through the portal.
- Wham Line: The following line from Jack uses to end his conversation with Nikolai before departing to get back to work, indicating that he's hiding some serious inner pain and loneliness under his happy go lucky jokester exterior:Jack: Anyways, you're wrong. People don't like me - they just laugh at my jokes. There's a difference. A big difference.
- Why Did It Have to Be Snakes?: As much as he loves all animals in general, Leon is not ashamed to admit that there are many types of invertebrate that unnerve him, with spiders in particular being the only invertebrate amongst this category that he's unambiguously terrified of.
