The constant innuendo to lbt 1 and 2;
Constant may be a bit of an exaggeration, but there were certainly more such references than in previous movies, and I think, up to this day more than in any LBT movie including LBT 10.
The mentions were mainly the really beautiful one of Littlefoot's mother in the song "Always There" which did not however directly refer to any scene from the original movie. I would love to hear a mention of "Some things you see with your eyes, others you see with your heart."
The other mention was the "summary" of who Chomper was. It refered more directly to the events of LBT, mentioning the eggeaters, yet I still suppose it to be intended mainly to give anybody who didn't see LBT 2 a very vague idea of who Chomper was. The message was mainly: "They know this sharptooth an they are friends."
Chomper having 3 fingers instead of 2;
This fact was a few time mentioned in other discussions somewhere. I suppose the reason is a practical one. They needed a Chomper with proper hands in LBT 5. It might have looked strange to have him drag the big leaf with the food for the gang holding it between two fingers. The scientifically correct depiction of the dinosaurs is not an extremely high priority in LBT (though higher than in some other dinosaur movies), so I suppose they just added one claw for asthetic reasons.
Cera still mistrusting him eventhough everything worked out ok in lbt 2;
Cera always seems to be disliked for this. However, I suppose that in a version of LBT 5 (or generally a story with Chomper) that wouldn't beat the bush about Chomper's being a carnivore as much as it is the case, Cera would appear much more reasonable. The way the whole problem is brought across in LBT Cera appears like a racist, almost like somebody who would get frenzy about anybody's skin color. It would be much more difficult to write a not so harmless LBT story, but it would do more justice to Chomper, Cera, and anybody else concerned. There is no way to deny that, by rescuing Chomper, Littlefoot and the others caused the doom of many other herbivores. I would expect Littlefoot to feel just a little more uneasy remembering the fate of him and his mother in the original movie. He probably caused the same fate to befall others. Does he ever think of his mother when he sees Chomper and his parents? In spite of LBT 5 being the first sequel to mention Littlefoot's mother we don't get the impression that he ever thinks about her while not singing the song. He doesn't seem to draw a line between the sharptooth who killed his mother an Chomper and his parents who are presented as more "cuddly". I don't suppose them to be any more evil or good than the sharptooth of the original movie if it comes to food. I think that Cera had some very good points, which were never elaborated in the movie as it would have made her appear more reasonable, and Littlefoot less so.
Chomper being able to talk, which he wasn't;
I suppose that Chomper must have had contact with other leafeaters since LBT 2. He also must have quite a good memory (remembering the first day of his life so clearly). The theory of his having contact with other leafeaters while under the care of his parents may be further enhanced by his mother's admonishon not to play with the food which might (but not necessarily) indicate that he played with "food" before. This however would probably cause Chomper some uneasiness, wouldn't it? If he has too much contact with what he has to regard as food? How would he deal with that?
That green sharptooth, species, Giganotosaurus maybe?
I'm quite sure it was a Giganotosaurus. There has been a long
discussion on the N54 forum about the species of the LBT 5 sharptooth. My reasons to agree that it was probably a Giganotosaurus can be found in that discussion in which theories of it being a Carnotaur respectively an Allosaur were raised.