T.J. really didn't do anything morally objectionable but is rather callous.
Bromley, the paleontologist is one of the more innocent of the bunch. But helps the group of gypsies steal T.J.'s horse in hope of following it to its home without a second thought of who the gypsies might hurt, or what the loss of the animal might do to T.J.'s show.
The Gypsies who take it upon themselves to free Gwangi from his cage in an effort to return him to the valley. At least two are killed for their troubles, and Gwangi escapes, killing Bromley and possible dozens of innocent people in the process.
Rooting for the Empire: Despite being seen as a scaly, bloodthirsty monster of a beast, it is very easy to root for Gwangi. Between the lifelike subtlest Ray Harryhausen gave it and the human cast being very easy to see as reprehensible in the modern day for environmental destruction and stamping on traditions in pursuit of making a profit, the final rampage by Gwangi easily comes off as a sympathetic Tragic Monster angrily lashing out much like King Kong before him.
Special Effect Failure: While most of the effects in the movie are still pretty spectacular to this day, even if just for the novelty craftsmanship involved, there are a few hiccups here and there.
The battle with the Pteranodon. The animatronic is a completely different color from the stop-motion model and moves much more limply.
Due to incorrect color timing, Gwangi's color changes throughout the entire film.
It is obvious that the sound effects used for the elephant are not from an actual elephant.
Spiritual Successor: Until the 1976 remake, it was arguably the closest thing to a remake of King Kong (1933) in color. The plot is similar if one accounts for change in location and dropping of the beauty and the beast angle.
Tear Jerker: Gwangi's death. His screams as he's trapped in the burning church are not those of some angry monster, but of a helpless and terrified animal desperately trying to escape. As everyone gathers around and watches the little Mexican boy Lope has tears in his eyes. Unless of course he was weeping over the destruction of that magnificent old cathedral instead. Strange, considering Gwangi is perhaps one of the least sympathetic Harryhausen creations and had tried to eat Lope without hesitation moments before.
The protagonists. Gwangi was just an animal minding his business in the Forbidden Valley until some greedy foreign businessmen show up to kidnap him and drag him off to be exhibited in a circus show. And then burn him alive.
The styracosaurus that Gwangi battles and reduces to a bloody heap. Only moments before, it had trapped Lope, Bromley, and Carlos in a cave and was presumably trying to kill them.
Values Dissonance: Both the depiction of the villainous, superstitious "gypsies" and the entire plot about capturing wild animals from an undisturbed ecosystem just to have them perform in a circus are horrendously outdated by modern standards. As mentioned above, it makes most of the human characters, including the protagonists, very unlikeable.
All of the prehistoric animals move very fluidly, even having specialized mechanism to emulate breathing and panting to add to the effect.
The editing to fit the humans and animals into frame with each other is virtually flawless, which wasn't at all simple a task when one considers this meant syncing up horse-riding lasso-throwing riders with a dinosaur that wasn't even physically there yet had to get snagged in the ropes.
Harryhausen's work on this is widely considered some of the most active and fluid dinosaurs in motion before Jurassic Park (1993). He was even invited to give talks about how large animals would move to students by actual paleontologists.
