More Popular Spinoff: The game and the anime is a spinoff of Mushiking. In the West Dinosaur King is far more well known thanks to the anime and card games actually being released overhere.
Angst? What Angst?: Rex is bizarrely fine with being uprooted from everyone and everything he's ever known and dragged back to the future by his birth parents. Yes, the Ancients are his birth mother and father, and yes they're nice people... but they're not his family. He's never known them, as he was separated from them as a newborn. Dr. Owen is the only father he's ever known, and Max and Zoe are repeatedly said to be like a brother and sister to him. He's never even BEEN to the Ancients' time... he was born in 65 Million B.C. and was lost on the way back. The Ancients are two people he's never known from a future he's never seen, demanding that he leave behind everyone and everything he loves to be with them... and it's just bizarre that no one, not even Rex himself, mentions how massively unfair that is, not even at the end of Season 2 when the time machine is broken and they explicitly state that he will NEVER be able to return to the modern day again, no matter what. Sure, Rex, says that he'll miss his friends, but you'd expect way more than that, and it never comes... Hell, the end of the first season is even worse, when he leaves without even saying goodbye to Dr. Owen, the man who raised him from a baby!!!! Seriously, what the Hell?!
The Alpha Gang in the first few episodes, actually. We don't actually see them doing anything evil until it's revealed that they brainwash the dinosaurs they capture. Before then, it just looks like all they're doing is reclaiming the cards that are rightfully theirs, and the heroes appear to be rushing into battle without even bothering to try to communicate with them.