Four American Bulldogs share the role of Chance, four Golden Retrievers share Shadow, and six Himalayan cat performers carry the part of Sassy.
Throughout the film, Sassy is seen licking her paws, sometimes as a haughty commentary on the superiority of cats. For this, fish oil was placed on the paws of the cat and naturally licked off.
The scenes of the pets walking along streets in city traffic were done with controlled vehicles only, traveling at very slow speeds. The truck sequence was shot in cuts. The dog ran from one trainer at point A, the release point, to a second trainer at point B who was giving the animal both visual and verbal commands. The street was cleared of all other traffic and the moving truck was filmed from behind. It was never actually near the dog.