The time has finally come to rescue the ruler of the dinosaurs itself, tyrannosaurus rex! With the entire rescue team ready and available, the mission to rescue t-rex is set into motion. But on this same momentous day that the team is at work in rescuing t-rex and any other appropriate animals to be found in Cretaceous Hell Creek Montana, they must also deal with rising tensions between Jack and Leon, keep an eye out for the dreaded KT-Event asteroid quite literally hanging over their heads, and an unexpected emergency back at the park.
- Adaptational Species Change: Cirrus is a Quetzalcoatlus in this continuity instead of an Ornithocheirus like he was in Prehistoric Earth.
- Amphibian at Large: Scapherpeton and habrosaurus are amongst the animals rescued, with the former being about 3 feet long and the latter about 4-5 feet long.
- Anger Born of Worry: Alice does NOT react well to Jack's especially dangerous Indy Ploy involving the brachychampsa and a single basilemys.
- Animal Stampede: Earlier in the mission, a herd of leptoceratops engage in one of these to escape from a pack of acheroraptor while said pack is distracted and alerted by the sound of a larger predator's bellowing (in reality a recording from Leon's broadcasting device). This naturally proves the moment where said herd gets rescued, with the entire acheroraptor pack following them through immediately afterward. Later, the t-rex family causes an entire gigantic mass combined herd of thescelosaurus, ornithomimus, edmontosaurus, pachycephalosaurus, torosaurus, and triceratops to engage in one of these over the course of the mission. This proves the point where said herd gets rescued, with only a single elderly adult ornithomimus failing to make it through before it gets successfully killed by the t-rex and carried off to be eaten.
- Armor-Piercing Question: Over the course of an argument they're having in the midst of the mission, Leon is noticeably left with great difficulty at giving an adequate response once Jack asks him what he legitimately has to offer to the park outside of encyclopedic knowledge on animals and a specially designed gadget with which he can 'talk' to the animals.
- Big Sister Instinct: Alice's protective instincts towards her brother very much rise to the forefront when he goes so far as to do a cannon ball dive right into the midst of a frenzied float of brachychampsa for the sake of rescuing a single basilemys at risk of getting eaten by one of them.
- Canon Foreigner: Newly introduced in this chapter are Jack's apparent friends amongst the reptile/amphibian keepers Aaron Joseph, Carmen Perez, Maria Gonzales, and Hugo Adams (the last of these four having previously been planned for Prehistoric Earth before getting cut for pacing and has since been repurposed for this story).
- Colony Drop: Unsurprisingly, the infamous K-Pg asteroid proves a major plot point for this mission.
- The Day the Dinosaurs Died: The K-Pg asteroid is featured, and is seen crashing into the Earth.
- Doomsday Clock: The sight of the meteor up in the sky prior to its infamous crashing upon earth, and its positioning in the sky over the course of the time before said arrival, is used by the team as a means of determining just how much time they have to rescue t-rex and whatever other animals from the area that they can before the infamous Colony Drop.
- Double-Meaning Title: The title Return of the King serves as both a nod to how Tyrannosaurus rex (the 'king' of the dinosaurs) is the target for this mission and a Shout-Out to The Lord of the Rings.
- Early-Bird Cameo: According to
Word of God from A-LionGleek, Will, Matt, and Kaisumi are present in a silent cameo alongside Alice and Khatin in the chapter's ending montage for the sake of doing research on some of the Hell Creek animals living in the forest building of the new exhibit zone. - Enemy Mine: Jack, Kaa, and Duke all hide peacefully inside a log in fear of a family of t-rex actively trying to hunt them.
- Escaped Animal Rampage: The male torvosaurus ends up escaping and very narrowly gets prevented from leaving the park's boundaries.
- Gentle Giant Sauropod: A single alamosaurus that is rescued (and named Custer) qualifies as this by virtue of being a very friendly and amicable fellow.
- Giant Flyer: Cirrus the quetzalcoatlus qualifies, as do all the other quetzalcoatlus present.
- Good Parents: Rexy and Tyrannor the adult t-rex prove to very much be this for their son Terrence and daughter Matilda.
- Headbutting Pachy: A pair of juvenile males amongst the pachycephalosaurus herd are seen butting their heads in a mock tussle at the park.
- Indy Ploy: Jack once again proves himself a master at this, much to Alice's horror and consternation. Drew himself also pulls out one of these (at Leon's unwitting expense) for the sake of recapturing the male torvosaurus after it ends up escaping from its holding pen at the veterinary facility.
- It Can Think: Duke the dromaeosaurus leader is at least smart enough to recognize Jack the second time they meet while in the past. He also seems to act briefly regretful when he escapes a log and leaves Jack and Kaa in the log as the t-rex family that happen to have cornered all three of them inside said log chase after him.
- Knight of Cerebus: The t-rex family in the first three scenes featuring them, as they are in the midst of actively hunting and prove reason for concern and suspense for the rescue team and any unlucky would-be pray animals in the area as a result.
- Let's Split Up, Gang!: Twice over the course of the mission, Drew and Adrian head in one direction while Leon and the Denhams head off in another for the sake of covering more ground and having higher chances of rescuing a larger number of animals alongside the t. rex before the KT-Event asteroid arrives.
- Mythology Gag: Has several similarities to the 'T-rex Returns' episode of the original Prehistoric Park series.
- Named After Somebody Famous: A single rescued alamosaurus is named Custer (after General George Custer), one of the subservient male pachycephalosaurus is named Einstein, and one of the palaeosaniwa is named Geronimo.
- Never Smile at a Crocodile: Thoracosaurus, champsosaurus, borealosuchus, and brachychampsa are amongst the animals rescued. The brachychampsa in particular prove particularly vicious to rescue over the course of a frenzy they end up undergoing after being triggered into revealing themselves for what they actually are by a small group of basilemys.
- Outrun the Fireball: According to Word of God, the rescue team and t. rex family both manage to just barely do so without even realizing as much by virtue of how a massive wave of fire brought about by the KT-Event meteor's impact comes roaring right through the area they'd just departed from literally seconds after the portal had closed behind them following their mutually successful rush through it back to the future.
- Pike Peril: Averted with the lepisosteus species rescued in this mission due to being caught at a time in which they weren't actively hunting.
- Raptor Attack: Averted. While dangerous animals in their own right, the acheroraptor, pectinodon, and dromaeosaurus aren't portrayed as being any more aggressive or vicious than any other ordinary animal. They are also accurately feathered, accurately sized, and portrayed as intelligent to a more realistic degree compared to the raptors from Jurassic Park.
- Shout-Out:
- Naturally, the entire episode is based heavily upon the very first episode of the original Prehistoric Park series. And the title functions as both a nod to the t-rex being the target and also to the title of the third entry in The Lord of the Rings.
- The T-rex family are named as follows; the mother is named Rexy, the father is named Tyrannor, and their son and daughter are named Terrence and Matilda. Furthermore, one of the quetzalcoatlus is named Cirrus, two of the juveniles triceratops are named Theo and Cera, and the alpha male of the pachycephalosaurus is named Sandor while also having a sister named Luxa.
- According to the authors, Drew's Indy Ploy to recapture the escaped male torvosaurus that ends up explicitly endangering Leon is one of these to the opening scenes with the Loch Ness monster in Missing Link.
- Finally, according to A-LionGleek, the moment where the rescue team and the t-rex family escape through the portal 'just in time' contains an implied one of these to the very end of the first season finale for The Umbrella Academy (by virtue of a wave of fire roaring over the area the team and t-rex family had been mere seconds after said groups have already exited through the portal and the portal has closed, much like how a similar situation occurred at the very end of the season 1 finale of the aforementioned series immediately after Five and his siblings had already vanished into the time stream to travel back in time).
- Snakes Are Sinister: Averted with Kaa and her fellow dinilysia rescued this mission.
- Social Ornithopod: Amongst the mass group of herbivores are a herd of thescelosaurus, a herd of edmontosaurus, and a herd of ornithomimus, all of which are happy to spend time together alongside each other and the pachycephalosaurus and ceratopsians present alongside them.
- Stealthy Colossus: The t-rex family don't get detected by the mass combined group of herbivorous dinosaurs (or the rescue team) in their first appearance until practically seconds before they enter the clearing. Similarly, Jack is completely unaware of the t-rex family being present in another clearing he's about to enter to explore on his own until literally after he's already entered said clearing and actually seen them there.
- Teeth-Clenched Teamwork: Still very much the case between Leon and Jack.
- Temper-Ceratops: Averted with the triceratops and torosaurus over the course of the mission due to them being seen browsing for food and running from the t-rex family in their scenes in the past. Nonetheless, two of the juvenile triceratops are seen engaging in a mock tussle at the park, so the species could yet qualify later in the story.
- Terrifying Tyrannosaur: The t-rex family showcase aspects of both the fearsome and noble portrayals of their species over the course of the mission:
- Fearsome: Act as The Dreaded and a Knight of Cerebus to the rescue team and the larger combined herd of herbivorous Hell Creek dinosaurs, and prove quite ferocious to match over the course of their efforts at hunting.
- Noble: Act surprisingly gentle around each other over the course of feasting upon a freshly killed ornithomimus immediately before the arrival of the KT-Event asteroid as well as in their scene in their new enclosure at the park.
- That's No Moon: Once again, an apparent group of logs turns out to be anything but.
- Theme Naming: Custer the alamosaurus, Geronimo the palaeosaniwa, and Sherman the denversaurus are all named after important people (or in Sherman's case, an important weapon) in military and warfare related matters.
- This Is Gonna Suck: The rescue team's reaction once the dreaded KT-Event asteroid breaks the atmosphere and strikes the earth. Also Leon's reaction when he notices a look on Drew's face that indicates he's about to resort to 'something crazy' for the sake of recapturing the escaped male torvosaurus.
- Threatening Shark: Very much averted for the quite small and seemingly quite docile lonchidion.
- Tough Armored Dinosaur: A small combined herd of ankylosaurus and denversaurus are amongst the animals rescued. And they are both creatures that neither the park staff or local carnivores are willing to go up against lightly.
- You Have GOT to Be Kidding Me!: Upon finding out just what is planned to be the target for the next mission, Leon reacts as follows:Leon: "ARE YOU SHITTING ME?!"
