Originally the dinosaurs where not going to speak at all and the film was going to be a silent, slightly less kid-oriented, animated documentary with narration. At the last minute the studio hastily hired actors to voice the dinosaurs after the animation had been rendered which is why the dinosaur's mouths don't move when they speak and when they do the lip synching is off. After the film was released it was panned by critics with the main criticism being the awkward voice-overs.
Although the fact that small, raptor-like dinosaurs were feathered has been known since the end of the nineties, this is one of the first movies to actually depict many of its dinosaur characters with a feathery coat. Jurassic Park III (2001) was the first movie to feature raptors with any feathers at all. Originally, Disney's Dinosaur (2000) would also have included feathered raptors, but budget and animation issues forced the creators to depict them incorrectly with scales.
The tyrannosaurs in this movie are scaly because their models had already been completed before sufficient evidence - such as the discovery of the giant feathered Yutyrannus - came to light in support of the idea that these animals may have been feathered in real life, but also probably because the creators felt that the public would be more accepting of the traditional, scaly look, which is now known to have been incorrect.