The size of the Ornithocheirus is vastly overestimated. It wasn't the largest flying animal ever to have lived, and its wingspan was probably only half of what the show says.
Just like the original series, this special also incorrectly identifies Tropeognathus (called Ornithocheirus here) as the biggest flying animal ever, with a wingspan of up to 12 m. In reality, the largest know specimens maxed out at around 6 m, and other flying animals, like Quetzalcoatlus, were much, much larger.
Pteranodon is shown with a somewhat shorter lower jaw, however in reality, their lower jaws were as long or longer than the upper jaws, and their beak pointed slightly upward, not straight forward.
In one shot, you scan see a Pteranodon leaning onto air.
In one shot, a Pteranodon can be seen resting one of its front legs "on" air.
The shadow effects of the Giganotosaurus chasing Nigel's jeep are animated incorrectly.
When Nigel throws a fish at a flying Pteranodon, the reflection of the animal on the wet beach is very faint, even though all other reflections are clear and darker.
At one point, a Pteranodon flies over Nigel, but it doesn't cast a shadow on him.
Argentinosaurus and Giganotosaurus didn't live at the same time, so the premise of the episode, that Giganotosaurus hunted Argentinosaurus, is erroneous.
Pteranodons are depicted as living 100 million years ago during the Aptian period, when they are only known the Santonian 85 million years.
When the Giganotosaurus pack attacks the Argentinosaurus, one of the predators can be heard roaring in the deep, grumbling voice of their prey, instead of its own sound.
No Pteranodon, nor any giant iguanodontids are known from South America from the time period this episode takes place in.