Goofs

When Chief runs after Tod, he is dragging his barrel after him, but when the shot goes to Copper, still tied to his own barrel and barking, Chief's barrel is next to his.

Amos drops three traps on the ground by Copper. Yet, when he sets them up, we see five traps. Furthermore, Tod springs about half a dozen traps, and there is one left for Amos to accidentally step into.

Copper sniffs around a small brook. In the next shot, the water's gone.

Tod's collar disappears and reappears during the night hunt scene.

After we first see Big Mama come out of her tree, we see a fox running towards a fence. Behind it on a clothesline, you can see a pair of blue pants hanging. In the next shot it is a blue sheet.

The chances of Chief being hit by a train and falling 50 feet from a bridge and surviving are slim to none.

Shortly after the night hunt, Big Mama is seen sleeping with Dinky and Boomer. Owls are nocturnal meaning they stay up at night and sleep during the day.

The bear that attacks Amos and Copper is supposed to be a black bear but it has the body type of a grizzly bear.

Chief is meant to be an Irish Wolfhound but is much smaller and less hairy than said breed.

It is extremely unlikely that Tod would survive falling down the waterfall. However, it is possible that the black bear landed first and provided a soft landing for Tod.

When the camera pans up to reveal a grown Copper in the front seat of Amos' car, the color in his eyes changes as he bobs his head.

During the part where Vixey shows Tod the forest, Tod's lips don't move when he asks her "Six what?"

When Vixey says "Come on." when showing Tod the forest, her lips don't move.

Tod shouldn't have survived the fall down the waterfall if the bear didn't, given the massive size difference between them.

Tweed tearfully abandons Tod In the forest to keep him safe from Amos. In reality animals that have spent their whole lives with humans or in resources like zoos etc. would not be able to survive in the wild as they would not had been taught by their parents on how to hunt for food or how to fight or hide from other predators etc.