Animals are the heart of this film, and apart from the canine and feline stars, a variety of other animals play major or minor roles.

At the outdoor wedding ceremony, a child holds a frog, which jumps out of the child's hands onto the grass. This scene was done in cuts and the frog jumped a distance of about two feet. The mischievous Chance finds the wedding buffet table irresistible and soon is wearing the wedding cake ear to ear. The dog portraying Chance loves whipped cream. A lot of cream was spread on him so he would not consume too much for this scene. Chance loves to tease the aloof Sassy by chasing and teasing her. The chase scenes were done in cuts. The cat was merely running to a buzzer while the dog came in response to verbal cues and was not actually chasing the cat.

In one scene Chance tricks Sassy onto a seesaw, where she gets catapulted through the air. This scene was done in many cuts. The seesaw lifted up to a height of about four feet and the cat was filmed on it. The cat was then filmed as she was tossed from one trainer to a blanket being held by several people. The cat seemed to love it and purred throughout. The camera angle facing up made it look as though the cat was at a height much greater than it was. A fake cat was also filmed flying through the air to give the perception of distance. Edited together it creates a spectacular scene. For the cat's landing, she was dropped by a trainer from a height of around two feet and landed in sand.

When they arrive at the farm, Chance chases a flock of chickens. This scene was shot primarily in cuts where the chickens were filmed separately. The chickens would be fed and then the trainer would wave his hands to make the chickens flurry away. The dog playing Chance was not really interested in the chickens, so the trainers would give him hand signals and verbal commands to stay, look in various directions, and stop, etc. to create the impression that he was after the chickens, but he was merely obeying his trainers commands.

The scene where Chance gets into a chicken house and the chickens scatter was filmed in basically the same manner. When a large turkey appears and chases Chance, the scene was shot in cuts, filming the turkey and the dog in much the same way as the chickens and the dog were filmed. Other animals seen on the farm primarily as atmosphere are a horse, a duck, a pig and some geese.

When the animals leave the farm each of the three goes over a fence. To accomplish this the scene was shot in cuts. Food was placed on top of a log which was put along side the fence. The trainer was on the other side of the fence by the camera. Each animal would jump on the log to get the food and then would jump over the fence, responding to the call of a trainer who was coaxing it over the fence with more food. Camera angles made the fence appear higher than it actually was and the ground was softened and padded with straw and covered with leaves and grass so that the landing was soft.

As Shadow leads the way and Chance and Sassy follow, the animals went from point A to point B, with one trainer releasing the animals as another trainer called to them. Along the way they see a raccoon, a skunk, a snake and an owl. As Chance chased the skunk, the skunk ran from point A to point B with food as a reward and the two animals were filmed separately. Most of the other shots of animals were filmed by a second unit that filmed nature in the wild and the footage was spliced into the scene with the animals.

The three hungry animals go fishing in a stream and Shadow lunges at one fish that he manages to get out. This scene was shot in cuts. To establish the fish a real fish was taken out of a special holding tank and placed on the river bank for less than four seconds, then returned to the tank. Chance chases the fish on the ground as the fish is flipping and flopping away from him. A rubber fish on filaments was used for this scene.

To get Chance to stick his head into the water, the trainers would put food on a rock and throw the rock into the stream and Chance would stick his head down to get the food. The fish used in this scene were kept in protective tanks which were then laid into the stream bed. While they are fishing they discover they have a companion who is also fishing. It is a bear who stands up and growls. This scene was also shot in cuts. There was no contact between the cat, the dogs, and the bear. The bear was given hand and verbal commands to stand up, smile, paw, etc. For safety purposes, wires undetected by the camera were placed between the animals.

The two dogs swim across a river, but Sassy doesn't want to swim so she finds another way of crossing by way of rocks and a log in the stream. The cat had been trained on her compound to jump from one rock to another in a stream. She also became accustomed to the water and could swim quite well. In the film the rocks and log had been strategically placed so the cat could jump from one to the other. When Sassy goes into the river, she was put in shallow water with a harness on her. She was then released by one trainer and swam to a second trainer who had a teacher attached to her harness. There were also four people under water to monitor her safety. Several cats had been trained for this scene. Each was only in the water eight seconds.

There are many shots of the cat being swept up by the fast-moving river as she heads for a very high waterfall. This was filmed using a fake cat. There are close-up shots of a frightened cat and then a shot of Sassy going over the waterfall. This scene was shot in many cuts. Fake cats, a mechanical cat, and a real cat were used. When the real cat was used, she was not in a river, but a heated pool. When Shadow attempts to rescue Sassy, and goes into the water, he is basically going from point A to point B in the water. Sassy is eventually rescued by an old woodsman who finds a lump of matted fur at the water's edge. He picks it up, hears a meow, and it turns out to be Sassy. The lump of matted fur which he first finds is the fake cat. When he picks it up the real cat was used. The cat was prepared for this scene by being sprayed down with warm water. The scene was accomplished in two takes. Around the woodsman's cabin a hawk is seen briefly in the sky and deer are also seen.

In the meantime, the dogs are hungry and Chance chases a rabbit hoping to catch his next meal. This scene was shot in cuts. After establishing the rabbit with the dog, the animals were filmed separately with each animal running A to B. With no success as a hunter, Chance tries fishing again. When Chance comes out of the water with a crawfish clamped onto the side of this mouth, a plastic crawfish was attached to the dog's mouth with a rubber band so that it looked as if it were hanging onto the dog's mouth.

While the dogs are fishing, a cougar spots the dogs from a distance and starts tracking them. Chance spots the cougar and tries to warn Shadow that the cougar is coming close, but Shadow has his head in the water and doesn't hear. Finally, Shadow lifts his head out of the water long enough for Chance to warn him. This scene was shot in cuts filming the dogs and cougar separately. A variety of A to B shots were filmed with the cougar in different locations. The dogs plan to rid themselves of the cougar by playing a trick on him using their old seesaw routine and Shadow as bait. They maneuver the cougar out on a ledge that juts out over a cliff. The entire area where they worked was all fake rock made out of hard Styrofoam. The plan is for Chance to jump on the other edge of the jutting area and catapult the cougar over the side of the cliff. Their trick is nearly ruined just as the cougar is about to pounce, when Chance is distracted and becomes fascinated momentarily by a butterfly that flies in front of him. For this scene silk butterflies were glued on the end of a fishing line and dangled in front of Chance's face. The dogs succeed and catapult the cougar quite a distance into the river below. This scene was shot in cuts with a very realistic looking fake cougar going over the cliff. When the cougar crossed down A to B, the dogs were not present and the cougar was filmed separately. The dog was filmed numerous times jumping onto a platform. All of this footage was edited together to make it look as though the cougar had been catapulted.

Sassy is fully recuperated and wants to get back to the dogs and her family so she leaves the cabin and runs off to find them. They have a very happy reunion. To increase the joy of this reunion some cat food was strategically placed on the dogs' faces to insure that the cat would nuzzle the dogs.

After their reunion, they have a fish feast along a riverbank and they eat their fill of fish. There is a pile of fish cadavers alongside them at the riverbank. All the fish cadavers were fake rubber fish.

Chance gets curious about a porcupine and goes toward it but the porcupine flicks his tail into Chance's face and injures him badly. Porcupine needles stick out of Chance's face and Sassy tries to remove them. The porcupine scene was shot in cuts with a real porcupine and a fake dog. They allowed the porcupine to hit the fake dog to show contact. Then rubber porcupine needles were attached to the side of Chance's face with spirit gum, which is a substance that actors use to apply beards and mustaches to their faces. To give the impression that Sassy is trying to pull out the needles, cat food was placed on the dog's face and the cat went for the cat food.

When the dogs are taken into the pound a blue muzzle is put on Shadow. The dog had been trained to wear a muzzle and was comfortable with it. He was able to take it off himself whenever he wanted to. A veterinarian removes the quills from Chance's face with pincers and the wounds look angry and sore. These wounds were totally fake and the dog was not at all uncomfortable.

Sassy, who had escaped the animal control officer, comes looking for the dogs and climbs the fence of Shadow's cage. (The cat was actually climbing to retrieve food that was placed on the lock and she was also responding to a buzzer.) Sassy rescues Shadow and releases him from his cage and Chance gets off the vet's table and there is a big chase scene as the animals run down corridors and the ACO's chase them. For this scene the animals were actually running and playing up and down the hallways of the filming area.

When they escape the building they run toward the surrounding fence. Sassy slips under a small hole underneath the fence. Shadow also manages to get underneath it but Chance, who is a little bit bulkier, becomes stuck. The three animals were each responding to the sound of buzzers. Chance was actually not stuck, but the director cut the film at precisely the right moment to make it appear as if he was. His backside is still on the pound side of the fence when a ACO grabs hold of him. Shadow throws himself at the fence, surprising the ACO, who lets go of Chance. When Shadow throws himself at the fence, he was actually doing a "foot-up", which his trainer had taught him. He was merely putting his feet up on the fence and the film was sped up to make it appear as though he was throwing himself at the fence. The three animals are off on their own again.

For the scene in which the animals go through a railroad yard and cross railroad tracks, no trains were in use while the animals were being filmed. Moving trains were filmed at a separate time and spliced into the film with the animals. While they are walking through this yard, Shadow falls into a pit and injures his leg. The dog never actually fell into the pit. When he stepped on the boards they broke, but there was a platform immediately below. Then a fake dog was dropped into the pit and these scenes were edited together. Shadow tries to get out but the pit is large and deep and muddy and he keeps slipping back into the pit because he cannot get a good grip. To accomplish this scene a special pit was dug which was about three to four feet deep. For the sliding back and forth, one trainer was at the top of the pit calling the dog. Another trainer was at the bottom telling the dog to stay. When he did he would naturally start sliding downward. The dog could actually walk out on his own at any time and did so several times during the filming.

When Shadow does appear at the end of the film to be reunited with Peter, Shadow runs with a limp. This was accomplished by putting part of a round wooden bead between the dog's toes. The bead did not hurt him in any way, but gave him a peculiar sensation, causing him to walk with a limp.