At the end, when Squeaks, the elusive caterpillar that Dinky and Boomer chase throughout the film, turns into a butterfly, it's a reflection on the larger plot where the hunters and prey reconcile.
When Copper starts leaving his barrel to go play with Tod, Chief makes a point to tell him how upset Amos Slade will be about it. True to this prediction, Copper is put on a leash for his misbehavior. Before Copper started wandering off, what was the biggest difference in how Amos Slade treated Chief and Copper? Chief was always kept on a leash. He had been trying to warn Copper about losing his privileges the same way that he did when he was younger.
Chief is dramatically outshone in tracking abilities once Copper shows up. Old age? Not likely. Chief looks like a shaggy greyhound-esque breed or mix—lean, tall, long thin muzzle, small ears, no wrinkles. In other words, he's a sighthound. Sighthounds are bred for just that—flushing and chasing prey based on line-of-sight, working in tandem with the handler. Scenthounds like Copper have been designed through thousands of years of breeding to locate prey by smell alone. They're just built for different styles of hunting. Copper was always going to be better at the kind of tracking-heavy hunting style his master prefers.
Another bit of Fridge Brilliance is that those types of dogs are often used together.
Slade is completely taken aback when Tod and Vixey jump through the burning grass blocking their escape from the foxhole. Any wild animal would instinctively flee fire, but Tod was semi-domesticated, and had been by Widow Tweed's fireplace before.
The movie begins with the baby fox's mother hiding him and sacrificing her own life for his, Bambi-style. However, foxes almost never have a single cub. This mother wasn't just carrying her baby to safety. She was carrying to safety the only baby of the litter who survived the hunt.
It's a good thing this is a Disney movie, or the movie would have ended as soon as Big Mama saw a newborn fox cub left by its mother—great horned owls eat fox cubs if given the chance in real life.
Although it's more like Fridge Sadness: The end of the film pans out on Tod watching Copper from a hill. It was earlier shown that the widow drove what was possibly hours getting Tod to the reservation, meaning he traveled a long while to look at Copper and his old home one last time.
While trying to get Tod to understand the harsh reality that Copper, as a hunting dog, will have to become his enemy, Big Mama, Dinky, and Boomer show him Amos's shack of animal skins. At least one fox pelt can be seen.
Between the burning grass and Copper, Tod chose to try his luck by jumping through the flames. Copper used to be Tod's best friend, and now he became scarier than the fire.
When the bear hits Tod or Copper, he sends them flying, but when he hit Amos all he did was knock him down the hill. Amos is heavier than them, but bear also uprooted a dead tree so that probably didn't factor in. But given how lightly he seemed to hit Amos, it gives the hint that the bear was just trying to knock his gun out of his hand. Between that and how the bear slows down when it looks like his victims are down for the count and winds up more before trying to strike them (and rather oddly only uses his teeth once), paints the bear as especially cruel and that he enjoys frightening his victims before killing them. After Amos shot him the bear wanted him to feel helpless in retaliation for shooting him.
Why did Amos Slade keep Chief on a leash but let Copper go unrestrained? It's all well and good to teach your dog to stay near your house on its own accord while it's still young, but shouldn't Slade have been personally watching him during this learning period? There are wild animals all around their house! A puppy Copper's size could geteatenif it wanders too far.
In the time period this takes place in, especially in a rural home, this would have been normal animal care. Doesn't make it any better or more sensible, but it fits the mentality of the time.
Adding to this, from what's implied, Chief did what Copper did and that's why he's chained up, so the reason why he might have been allowed to wander around probably wasn't because he allowed to wander around in a sense, just that he had to learn to stay on the property (how Slade expected to accomplish this without actively training Copper is Fridge Logic in itself) or that he expected Chief to keep him out of trouble (again, also Fridge Logic).
Is Slade going to be arrested for trespassing onto a game preserve? Hunting license or not, Slade was poaching all because of a petty vendetta.
He was never caught and Widow Tweed probably wouldn't turn him in even if he was willing to admit how he got hurt in the first place. All Tweed cared about was Slade trying to hunt Todd and Slade had given that up by the end of the film.
When Tod is getting to know Vixey, Dinky and Boomer suddenly show up out of nowhere to watch them.
During the bear attack, Amos Slade struggles to reach for his gun since his foot is caught in one of his traps. The trap is clearly seen being held down by a post; it would probably take less effort to pull it out of the ground and go for the gun rather than try to pry the trap open.
Panic, most likely. Amos probably wasn't thinking rationally, and even as a man with obvious survival experience, it's quite possible that in the chaos pulling the post out of the ground didn't occur to him.
Also, taking the post out might waste time. Those posts are embedded deep in the ground so the animal can't just run off with the trap. Slade would probably have to kick it several times with his good foot, jiggle it around, and then reposition himself into a kneeling position to pull it straight up out of the ground two handed. All the while the trap would be tearing up his leg whereas removing the trap simply requires him to get in a kneeling position and using leverage and gravity to force both sides down until the trap locks back into place then he could get the gun. Not that the type of ammunition Slade had would be at all effective on a bear, mind you, but he was hellbent on saving his dog's life. While he could potentially play dead and let the bear smack him around for 20 minutes, he would be extremely injured and unable to make it back to his car and Copper would almost certainly be dead. Playing dead isn't always effective against bears. Sometimes they will claw, bite, and smack around a "corpse" just for the hell of it. Especially black bears which are much more vicious than brown bears. Slade almost certainly knew that and was desperate.
How exactly did the bear hitting the log cause him to fall? We only see him hit the branch Tod was holding onto, then suddenly the entire log falls. Was this an animation goof and the bear was supposed to break the log in half?