Character mistake: Throughout the entire series, the Turtles are referred to, by others and by themselves, as amphibians. But turtles are reptiles, not amphibians. However they are amphibious, amphibious reptiles.
Other mistake: When LB comes into Tweeg's room and he sees him covered in spots and he is discoloured he freaks out. Why does he freak out? He just saw Tweeg in the previous episode all covered in spots so he should know that it's him.
Revealing mistake: The "hostage" episode reuses footage from the "Dinosaur" episode, which doesn't totally fit. When the giant crabs attack and destroy the group of houses on the island, the longshot of the damage is recycled from the earthquake episode - including an earth fissure, something the giant crabs wouldn't and probably couldn't have done.