Most of the night scenes were shot during the day. At night, dogs tend to go to sleep wherever possible.
The electronic press kit for the film sent to media included a video showing an increasingly irate Mr. Tinkles screentesting unsuccessfully for several famous movie roles. These scenes can be found on the special features on the DVD.
The animation of the animals' mouths was done by Rhythm & Hues, who had previous experience with this style. They had provided the animation for the animals in Babe (1995).
Tobey Maguire's performance in this film was inspired by Keanu Reeves in the Matrix.
Prada, the Beagle who played Lou, also played Porthos in Star Trek: Enterprise (2001).
Buddy is a Bloodhound. Butch is a Karabash (Anatolian Shepherd Dog). The agent puppies and their commander are Dobermans. Lou is a Beagle. Peek is a Chinese Crested Hound. Sam is a Bearded Collie or an Old English Sheepdog. Ivy is a Saluki. The HQ dog is a Collie. The dog in charge of operations is a Mastiff. Mr. Tinkles is a Persian. Calico is an Exotic Shorthair. The Ninjas are Siamese (Oriental Shorthairs). The Russian is a Russian Shorthair. At the world Dog Council, the countries are represented by the following breeds : China - Shar Pei. Germany - Alsatian (German Sheperd). South Africa - Airedale. Cote d'Ivore - Cairne Terrier. Albania - Dalmatian. Afghanistan - Afghan Hound. Wales - English Bulldog. Mexico - Chiuahaha. Belgium - American Bulldog. Malta - Basset Hound. France - Poodle.
In a lot of instances, the puppeteer was in shot only to be digitally erased afterwards.
To get the dogs to lick their genitals on demand, peanut butter was applied to the necessary areas.
In the soccer stadium scene, Production Designer James D. Bissell is the face of the fake cardboard standee of the parking lot guard.
The scene where Sophie revives Mr. Mason, by pounding on his chest, was filmed in reverse.
The cat puppet in the film cost 4,221 dollars. The director wanted to do the film entirely in CGI. However, that would have put the film twenty-five thousand dollars over budget.
The mother in the film wears an "Ask me a real estate question" pin. She would remove it between takes, because the crew on-set would relentlessly ask her real estate questions.
Robert Rodriguez turned down the opportunity to work on this film, in order to continue work on the Spy Kids franchise.