Jurassic
Leedsichthys size is grossly exaggerated. In reality, it was 8–17 m rather than the 27 m in the show.
Leedsichthys had a smoother, more elongated head than in the show.
Same issues with Liopleurodon as in Cruel Sea. (see above)
Cretaceous
Pteranodon were diving creatures that hunted fish similar to gannets, unlike the skim feeders they were portrayed as in the episode.
Same other errors with Pteranodon as in Chased by Dinosaurs
Tyrannosaurus did not live 75,000,000 BCE. Probably the dinosaur featured in the show was actually Daspletosaurus.
Mosasaurs, like Tylosaurus and Halisaurus, and plesiosaurs, like Elasmosaurus, are believed to have had more pronounced tail flukes instead of lizard-like tails.
Tylosaurus was 14 m long, not 17 m long.
A recent study on mosasaurs has concluded that they were likely mainly black or dark in color, with a more whitish underbelly, not brown like the series' depiction of the animal.
There is no certain evidence that mosasaurs like Tylosaurus lived in large family groups. Although, it is still possible that they gathered in large groups (not necessarily family groups), like many snakes, their closest living relatives (i.e. garter snakes).