The cover of this issue depicts a T. rex squaring off against a Triceratops. The ridged backbone of the Triceratops may by a nod by artist Fred Himes to famed dino-artist Charles R. Knight's 1901 depiction of said beast.

Page 1 claims that the lifespan of a T. rex could cover hundreds of years! However, paleontologists believe it was much less, around 30 or so years.

Page 1 refers to the rogue rex as a Methuselah. Methuselah is the grandfather of Noah in the Bible and is allegedly the oldest man to ever live, at 969 years, according to most versions of the book.

Page 1, panel 1, features art of the rogue rex, a Saltoposuchus, and an Archeopteryx.

Page 2, panel 1 features art of what appear to be a Brontosaurus, a Pteranodon, and some kind of duck-billed (Hadrosaurid) dinosaur.

The dinosaur on page 3, panel 4 appears to be a Parasaurolophus. 

The tribe from the other valley states that they are fleeing from Godon, the rogue rex. A tyrannosaur also referred to as Godon was depicted in "A Turned Turtle", though that "tyrannosaur" had three claws on its forelimbs instead of the proper two, was green instead of bluish, and had a row of standing scales on its back. The Godon presented here seems more as if it's based on the Allosaurus from the 1969 film The Valley of Gwangi than the Godon from "A Turned Turtle".    Oddly, in both stories it seems as if the Butlers are encountering Godon for the first time; it seems more definitive though that "A Turned Turtle" was the actual first meeting of the Butlers with the beast.    The valley from which the other tribe has fled is presumably the valley of the Three Giants, where Godon was said to live in "A Turned Turtle".
Godon in "A Turned Turtle"	Godon in "Rogue Rex"	Gwangi from The Valley of Gwangi.

Page 5 shows that the tribe from the other valley knows John Butler's name even though they have not been properly introduced. Maybe the legend of the strange newcomers to the Valley of the Dinosaurs has spread to tribes throughout the land. 

On page 6, panel 2, notice that, at Godon's approach, Glump is covering his eyes with his forelimbs and Digger is on his back either fainted or playing dead!

The Tyrannosaurus/Triceratops fight on page 8 may also have been influenced by the Allosaurus/Styracosaurus fight in The Valley of Gwangi.

The flying creatures in the distant background of page 8, panel 6 and page 11, panel 6 look like they are probably Pteranodons.

John has the two tribes use bow and arrow to help drive Godon away. This suggests the story takes place after his first introduction of the bow and arrow to the cave-dwellers in "Smoke Screen".

Page 10 describes John as setting the archers of the tribe in double file, like in the American Revolution. During the American Revolution against the British from 1775-1783, the American militias did tend to march and fight in double file (i.e. a queue two persons wide).

On page 10, John tells the archers not to fire at Godon until they see the red of his eyes. The normal phrase is "Don't fire until you see the whites of their eyes", most popularly known from the battle of Bunker Hill during the American Revolution in 1775. In close-up panels of Godon in the story, the beast's eyes are depicted as a demonic red.

After successfully catapulting a pot of flaming oil onto Godon and driving him off, Greg remarks on page 11 that he only needs four more to become an ace. This is a reference to a flying ace, an air combat pilot who shoots down five or more airplanes of the enemy forces.

On the last panel of the story, Greg stencils a silhouette of Godon on the oil pot and writes on it the phrase "the Red Hot Baron". This is a play on the nickname of the German WWI flying ace Baron Manfred von Richthofen, the Red Baron (for his "Baron" family title and the red color of his fighter plane). Richthofen is officially credited with at least 80 air combat victories. Of course, Greg has added "hot" to his title to signify the flaming oil used against Godon. 

Unanswered Questions

What is to become of Godon? The beast is driven off by the tribes, but is still alive at the end of the story. But the beginning of the story suggests that he is growing old and is no longer capable of hunting the more swiftly-moving creatures of the valley besides humans. Was this Godon's swan song?