It plays it straight. Sid and Manny find a human baby, and decide to take it to the adults. The whole reason the baby got separated was because of an attack by saber-toothed cats, and the cats still want the baby. Enter Diego, who promises to help Sid and Manny deliver the baby to the tribe. They don't trust him, and for good reason. Throughout the film, nobody trusts Diego, and he threatens to eat Sid on several occasions. Indeed, the whole reason he's helping them is to deliver to his pack so he can eat them. He does a Heel–Face Turn, and saves them from the pack. This is all well and good, makes for a happy ending, but what is Diego supposed to eat? Diego's group of Sabre-tooths respected humans as fellow hunters; they were originally just after the human baby in revenge for the humans killing one of the sabre-tooths first; they weren't after it as a snack, per se, but only in retaliation. Apparently if Diego just told them this, then Manny could have told him that the baby's mother was already dead, and Diego could go just home since they were even.
At the end of the first movie, and throughout the entire second movie, Diego is seen happily hanging out with the sloth and the mammoth. Either he's fine with never eating again, or they just look the other way when he kills and devours their friends.
The third movie also parodies the vegan carnivore option by having Sid try to teach baby T-Rexes to eat fruit. When the real mother drops off a piece of meat for her offspring, they instinctively devour it, prompting a smug smile from her.
Also in the third movie, Diego actually tries chasing a talking deer. He's too slow to catch it.
In Shark Tale, Lenny the Shark, a principled vegetarian who refuses to devour sapient creatures, and massive disappointment to his father, makes an unsuccessful attempt to eat a sobbing shrimp who begs for his life.
And in a clear case of Artistic License - Biology, when he wants to look harmless to the fish population, he dresses up as a dolphin, even though fish are the food of choice for dolphins (Can you say "Dolphin Safe Tuna"?). It seems only sharks are afraid of dolphins. Yes, the badass predators of the deep are terrified of a dolphin, but the small little fishies don't even bat an eye. (OK, in real life, dolphins have been known to battle sharks that stray too close to their pods, but...)
In Happy Feet, the penguins themselves eat fish, which are rendered realistically. The pair of orcas encountered during the film are also treated realistically; as playful, giant dolphins that try to eat the protagonists. The Skua that try unsuccessfully to feed on juvenile penguins talk, and are depicted like bullies or gangsters. A leopard seal can speak and is treated like an intelligent, evil monster, akin to a dragon. Top this off with heavy, Anvilicious doses of Humans Are the Real Monsters and you've got yourself a very mixed bag on predator treatment.
In the sequel, the krill are able to talk (though not to the penguins) and realize how much life sucks on the bottom of the food-chain.
According to an Expanded Universe source, the reek beast (the red and gray rhino-like one) shown in the gladiator arena in Attack of the Clones was actually a herbivore. The Nemoidians discovered that if they were kept hungry long enough and fed only enough plant matter to maintain their health, they'd willingly attack and devour animals. (Meaning cruelty to animals is another atrocity that you could add to the growing list of crimes committed by the Trade Federation up to that point.)
At least in the PC game, the owl spoke. It was pretty creepy.
Abigale: What are you going to do with me? Owl: You'll figure it out...
The movie Madagascar addresses this directly. Alex, the main character, is a lion raised in captivity, who is used to being fed steaks, and is blissfully unaware that his friends are his natural prey. After being stranded in the titular island, and cut off from his beloved steaks, he slowly goes mad with hunger and reverts to his animal instincts. Now his best friends look like steak to him, and he exiles himself to the other side of the island. At the end, the situation is resolved by Alex becoming a fish eater. Meanwhile, Madagascar's native predators, the fossa, are depicted as dim-witted, Hulk-speaking brutes.
And then for some reason utterly ignored in the sequel, "Escape to Africa", where most of the animals live in harmony under the rule of a benevolent pride of lions, never minding the fact that a lot of the animals under their rule are a major diet source for lions in real life.
Kung Fu Panda also avoids the issue, since the Furious Five are carnivores or omnivores (Monkey and Crane), but all we ever see them eating is...noodles. (Granted, it's the only thing the herbivorous Po knows how to cook, and coming from a village where all the denizens are prey species — rabbits, geese, pigs, sheep, etc. — kind of makes that a no-brainer. But still...) Even Tigress, who initially refuses Po's dinner thanks to the continued chip on her shoulder, instead eats a plate of tiny tofu. Po only eats things like cookies, peaches, and dumplings, hopefully not stuffed with meat (though, thankfully, not bamboo). The only character we can assume to truly eat meat, due to his size, personality, and mental state, is the villain Tai Lung...and rather having a bit more on his mind at the time, we never see him eat either. The fact that, according to Word of God, the villagers were deliberately designed to be prey species in order to seem more helpless and timid before Tai Lung's ravages, on the other hand, treads very close to crossing the cannibalism line of this trope — and purposefully so.
Word of God has also stated that everyone in this universe is vegetarian, which completely averts this trope, but just raises more questions...
This is played straight as an arrow in the original, Don Bluth-directed The Land Before Time film, in which carnivorous dinosaurs are the main villains. Petrie's diet isn't mentioned in the first movie, but he's a Pteranodon, which were fish-eaters in real life.
Things get a little more awkward in the non-Bluth sequels with the introduction of Chomper, the friendly Sharptooth. The first few films where he shows up, it is made very clear that he could not possibly live with the main characters long term because of his dietary needs, particularly in the fourth sequel, with the song "Friends for Dinner" in which Chomper looks for leaves and berries to entertain his herbivore friends, while said friends fear that he's going to eat them. However in the spin off television show, this has been Hand Waved with him just surviving on insects, to justify upgrading him to main character status. Petrie is also revealed—along with the rest of the Pteranodons in the setting—to be an herbivore in the sequels.
The scene where Mrs. Brisby, a mouse, must seek advice from the Great Owl in The Secret Of Nimh is very up-front about this. The owl's home is littered with the skulls of mice the owl had eaten and the entire scene has an ominous air. Mrs. Brisby spends the entire experience scared out of her mind:
Brisby: Owls EAT mice! Jeremy: Uh...only after dark!
In the book sequel, Rasco And The Rats Of Nimh, the Owl nearly kills Timothy Frisby by snatching him up to eat until he realizes that Timothy is Mrs. Frisby's son. Timothy is really, really hurt badly.
Additionally, the only film that plays Cats Are Mean even heavier is...
An American Tail, also by Bluth. Here, Cats are not only Mean, they represent the various hardships faced by the immigrants to the U.S. in the 1800's. The one "good" cat, Tiger, is a vegetarian.
El Arca has a music number in which a panther sings about her right to eat meat in a parody of Gloria Gaynor's "I will survive" song. The movie's plot involves this trope as well: the herbivores are afraid to board Noah's ark because of the carnivores.
Somewhat parodied in Enchanted. Giselle can call on animal friends to help her. When she does so in the real world, she gets an assortment of "city animals" (rats, pigeons, flies, and roaches) to help her clean. They work well together during the cleaning song, but once it's over, a pigeon nonchalantly turns to the roach next to it and gobbles it up.
Open Season: It's never explained why the other wild animals in the forest never run away in fear at the sight of Boog, who happens to be a domesticated grizzly bear. Did the animals enter some kind of truce or something? Because there's a scene where Eliot's bully, a mule deer, actually taunts Boog in front of his face!
Maybe they can sense his incompetence and know they're in no real danger. It's not like Boog has the skills to hunt and kill the animals even if he wanted to.
Bears are Omnivores.
Incredibly epic fail in Pride which shows a vegan lioness doing pretty well until both plant and animal are depleted in the 'badlands' area where she lives after running away from her parents for them trying to force her to obey her carnivorous nature. Its essentially vegan propaganda aping the appeal of the flood of lion movies after. Also Sean Bean as a big macho lion badass probably didn't hurt funding either. In the end the entire vegan subplot vanishes to make way for a more traditional good lion/evil lion showdown as the lions from the badlands attempt to take over the heroine's pride.
The Over the Hedge cast don't seem to take into account the source of all the food items they take. Vincent threatens to kill RJ and naturally is the only non-human antagonist.
An in-movie bit in Babe, when Farmer Hogget somehow assumes Babe killed the sheep. Pigs are omnivorous and have been used to 'hide' bodies in the past by feeding them chopped-up corpses... but Babe is still a piglet, so it's unlikely he could kill a grown sheep.
How to Train Your Dragon had the giant Green Death dragon swallow an unfortunate Gronckle who failed to give it enough food. This is hardly surprising since a lot of animals have no qualms eating other animals related to them such as cobras eating other snakes, lions eating cheetahs, etc.
Actually inverted in The Mouse and His Child. The two (clockwork) mice are captured by a hawk. The child asks, innocently enough, what the hawk intends to do with them:
Child: Mr. Hawk, where are you taking us?
Child: What's "lunch"?
(The hawk bites into Father Mouse, but quickly realizes that they're just fabric and metal)
Hawk: You're not part of the balance of nature! (drops them unceremoniously and flies off)
We're Back! A Dinosaur's Story: Thank to Captain Neweyes' "Brain Grain" cereal, the dinosaurs he feeds become intelligent and non-carnivorous. Well, sort of. Though Rex apologizes for if he might've attempted to eat any of his new friends, the Triceratops is shown eating hot dogs. Tofu dogs, maybe?note It's been speculated that Triceratops might have been an omnivore, but this film was released well before that theory. According to Neweyes, his Brain Grain has brought about world peace in the distant future due to no carnivores. Apparently the future hasn't had any problems thus with overpopulation or malnutrition.