Dexter's Laboratory is the first of three pilot shorts of the Cartoon Network original series, Dexter's Laboratory, followed by "The Big Sister" and "Old Man Dexter". The short premiered on Cartoon Network as part of the showcase series, What a Cartoon!, on February 26, 1995.
While Dexter completes his greatest invention yet, a device that can change humans into animals, Dee Dee enters his lab and accidentally uses the device on Dexter transforming him into a bunny. In return Dexter uses the device on Dee Dee turning her into a frog. Dexter then tries to explain the device to Dee Dee while she uses it to turn him into many different animals (pig, water buffalo, orangutan, ostrich, hamster). Dexter in turn uses the device on Dee Dee transforming her into a tiger, which scares Dexter, causing him to run. Dee Dee chases him while using the device to transform him into some other animals (cow, walrus, penguin). Dee Dee then slips on a roller skate causing the device to fall in between the two siblings.
They then use the device to change each other into several different animals (camel, vulture, snake, whale). Mom then tells them to brush their teeth and the two are seen as a dinosaur and a beaver in the bathroom brushing their teeth. The two then sit down with Mom to have breakfast, as a chicken and a bear, until Mom (who does not notice they are animals) tells them to get ready for school. The two then fight over the device while transforming each other into many different animals, until Mom enters Dexter's room and the viewer sees Dexter and Dee Dee on the floor back in what appears to be their normal bodies. Unfortunately they are actually in each other's bodies.
- Art Directors - Craig McCracken, Paul Rudish
- Created, Written & Directed by - Genndy Tartakovsky
- Executive Producer - Buzz Potamkin, Fred Seibert
- Supervising Producer - Larry Huber
- Line Producer - Bob Onorato
- Unit Production Coordinator - Nicole Pouliot
- Design Assistants - Donna Zeller, Dana Jo Granger, Barbara Krueger
- Recording and Casting Director - Kris Zimmerman
- Talent Coordinator - Jill Ziegenhagen, Cindi Lyn Peltier
- Supervising Sound Engineer - Ed Collins
- Recording Engineer - Preston Oliver
- Music Score by - Pete Houser
- Main/End Title Theme by - Gary Lionelli
- Director of Music Production - Bodie Chandler
- Background Stylist - Martin Ansolabehere, Jane Nussbaum
- Background Supervisor - Al Gmuer
- Background Artists - Joseph Binggeli, Bonnie Callahan, Jonathan Goley, Craig Robertson, Leonard Robledo
- Ink and Paint Supervisor - Alison Leopold
- Color Stylist - Casey Clayton
- Final Checker - Nelda Ridley
- Ink and Paint Artists - Etsuko Fujioka, Meling Pabian, Lydia Swayne
- Additional Layout Artists - David Fulp, Virginia Hawes, Craig Kellman, Miles Thompson
- Graphics - Iraj Paran
- Camera Operator - Dan Larsen
- Executive in Charge of Post-Production - John Forrest Niss
- Animation Checking - Beth Goodwin
- Xerography - Star Wirth, Martin Crossley, Richard Wilson
- Track Readers - Kay Douglas, Jim Hearn, Carol Iverson, Kerry Iverson
- Supervising Film Editor - Tom Gleason
- Post-Production Supervisor - Gayle Mnookin
- Post-Production Coordinators - Valerie Menk, Gail D. Silvers
- Sound Services Provided by - Advantage Audio
- Sound Editor - Michael Warner
- Re-Recording Mixers - Bill Koepnick, Jim Hodson
- Negative Consultant - William DeBoer, Jr.
- Video Services Provided by - Four Media Co.
- Telecine - Scott Ostrowsky
- On-Line - Brian Schnuckel
- Pre-Production Manager - Debby Hindman
- International Production Coordinator - Brooke Williams
- Production Assistants - Sandra Benenati, Duke Heberlein, Linda Moore
- Executives in Charge of Production - Joe Mazzuca, Catherine Winder
- Program Executive - Margot McDonough
- Production Coordinator - Sylvia Edwards
- Development Executive - Dan Smith
- Production Company - Hanna-Barbera Cartoons, Inc.
- Produced in Association with - Fil-Cartoons, Jaime Diaz Productions
- Overseas Animation Director - Jaime Diaz
- After Dexter's Laboratory was picked up as a series by Cartoon Network, this short was renamed "Changes" for all subsequent airings.