The Asian man who feeds the pups at the beginning of the film is speaking Vietnamese. He says, "You must be hungry. Eat a lot so you can grow up."
Contrary to popular belief, Fluke was portrayed by canine actor Comet (Buddy), known for his role in a few episodes of Full House (1987).
In general, the dogs were very well trained in pre-production to respond to verbal and physical commands and were rewarded with food. In scenes where the animals moved from A to B or appeared to be chasing another animal, they were actually responding to a trainer's command and ran to another waiting trainer who rewarded the animal with a treat. When the animals appeared to be in an agitated state or growling, they were actually responding to the trainer's hand and verbal commands. During any attack training and during filming of the attack scenes, the dogs were prompted by a trainer who used both verbal and physical commands. The dogs were not bothered by this activity, but returned to a playful state immediately and then given verbal and food rewards. Another technique used by the trainers to give the appearance of agitation was to encourage play behavior with the use of towels, balls and noise makers.
There are two scenes in which it appears as if Fluke is about to be hit by a car. These scenes were shot in cuts and the animals were not near the moving vehicles. While the dogs appear as if they are wandering the busy city streets alone, trainers were present just off camera at all times and the animals were merely responding to trainers' commands and moving A to B. The scenes were always well choreographed and the traffic was either stopped, or when moving, the animals were held by their trainers and kept forty to fifty feet away. When the car looks to have stopped short of hitting the puppy, the scene was shot in cuts. The car was stopped at least four feet from the animal when the pup is seen crossing directly in front of the car and the trainer was right there to receive the dog and reward him with food. For the running scenes, several dogs and their doubles were used so that no one dog was ever tired.
Nancy Travis and Matthew Modine previously appeared in "Married To The Mob."