The look of the dinosaurs
Probably a minor thing to some, but I didn't think they really nailed the look of the main characters. Spot was fine, but Arlo and his family looked a little TOO cartoony especially with their big eyes, which conflicted with the realism of the surrounding landscape.
I found it a little offputting, though I concede I may be looking at it too much through the eyes of an adult given it is a kids film.
You know it makes sense