Most of the night scenes were shot during the day. At night, dogs tend to go to sleep wherever possible.

Tobey Maguire's performance in this film was inspired by Keanu Reeves in the Matrix.

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.

Prada, the Beagle who played Lou, also played Porthos in Star Trek: Enterprise (2001).

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.

To get the dogs to lick their genitals on demand, peanut butter was applied to the necessary areas.

In a lot of instances, the puppeteer was in shot only to be digitally erased afterwards.

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.

In the soccer stadium scene, Production Designer Jim 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.

Robert Rodriguez turned down the opportunity to work on this film, in order to continue work on the Spy Kids franchise.

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).

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 red cell phone, used by Elizabeth Perkins, was the Nokia 8290.

American Humane Association monitored the animal action. No animals were harmed. Scenes appearing to place animals in jeopardy were simulated. AHA ® 00133

Ving Rhames were considered for the role of Sam.

Leonardo DiCaprio were considered for the role of Professor Brody.

Jennifer Aniston were considered for the role of Mrs. Brody.

Michael J. Fox were considered for the role of Lou.

Bryan Cranston were considered for the role of Butch.

Renée Zellweger were considered for the role of Ivy.

Ray Romano were considered for the role of Peek.

Danny DeVito were considered for the role of Peek.

Alan Cumming were considered for the role of Mr. Tinkles.

Trey Parker were considered for the role of Mr. Tinkles.

Calista Flockhart were considered for the role of Ivy.

Jane Leeves were considered for the role of Ivy.

Rip Torn were considered for the role of Sam.

Jack Nicholson were considered for the role of Butch.

Laura Dern were considered for the role of Ivy.