Template:Plot In the future, while Elroy is busy working on a time machine, George Jetson comes to Mr. Spacely's office for a serious discussion. Spacely's business rival, Cogswell, has been stealing Spacely's business ideas, putting their jobs in jeopardy, Spacely orders George to go spy on Cogswell where George finds out that Cogswell's robot computer, S.A.R.A., has been seducing the Spacely robot computer, R.U.D.I., into leaking Mr. Spacely's secrets. George tries to report to Spacely, but R.U.D.I. won't let him.
In the Stone Age, Wilma and Betty are trying to convince Fred Flintstone to have their vacation in Honolurock. Fred ignores their advances and tells Barney Rubble that he plans to take the girls someplace better. Mr. Slate wants Fred and Barney to work a late shift due, but instead they go to a poker game, hoping to use the winnings to go on holiday. Slate is at the poker game however, so Fred and Barney try disguising themselves. Fred loses to Slate, and he and Barney are exposed, so Slate fires them.
Back in the future, Elroy finishes his time machine. The Jetsons decide to use it to take a trip to the 25th century to relax. Right before Elroy gets the machine working, his dog Astro accidentally sets the switch to "Past".
With no job, the Flintstones and Rubbles are forced to settle for a camping holiday. As Fred and Barney set up the tent, the "Jetsons" arrive from the future. Fred and George eventually communicate and the families become friends. Fred is amazed by George's futuristic gadgets and decides to use them to help Mr. Slate at the competitions at the upcoming company picnic. Fred introduces George to Slate, claiming George is a distant cousin. Slate is reluctant at first to trust George, but since Mr. Tarpit's cheating has set him back in the competitions, Slate accepts their help in exchange for giving them their jobs back. George and Fred use George's technology to win the events. However, during the last event, which consists of catching a "pigasaurus" in the mud, Astro and Dino's continued chase scares the pigasaurus enough for it to jump into Tarpit's arms, making him the winner of the picnic. Enraged, Mr. Slate refuses to hire Fred and Barney again.
While Mr. Spacely continues to vent over his failing business, Henry and Rosie the Robot Maid assemble a 'time machine retriever' to bring the Jetsons back. But when they turn it on the time machine returns with the Flintstones instead. At first, Henry, Rosie, and Mac mistake the newcomers for the Jetsons, and so does Spacely. But upon seeing they really are cavemen, Spacely introduces them to the press.
Stuck in the past, George asks Mr. Slate for a job. Slate initially rejects, but when Tarpit offers George work, Slate immediately makes George his partner. George becomes famous. Using their new found fame and riches, the Jetsons buy multiple local businesses and are soon overwhelmed.
Mr. Spacely makes Fred the spokesman for his company, but R.U.D.I. leaks this information to S.A.R.A. When Spacely is introducing Fred to some important investors, Cogswell shows up and introduces Barney. Fred and Barney fight jealously.
Meanwhile, Rosie requests R.U.D.I. to help her and Henry try to fix the time machine to find the Jetsons. S.A.R.A. arrives and demands that R.U.D.I. get rid of Rosie, but R.U.D.I. agrees that he'll do whatever he can to get the Jetsons back and leaves S.A.R.A. for good. They fix the time machine w and Rosie is transported to the Stone Age where she finds her family.
Now able to return home the Jetsons leave, taking Fred's car with them, after Judy says goodbye to a teen idol. Mr. Spacely concocts a plan to use Fred's car as a model for futuristic replicas, and his business of selling Stone Age style cars becomes successful, much to Cogswell's dismay. Fred and Barney repair their friendship, and before they return home, George offers his partnership with Mr. Slate to give them their jobs back. Just as they are about to leave, Elroy tells them the time machine is broken and cannot be repaired. However, they're able to return to the Stone Age because their car absorbed the time machine's "quadrapotents". The Jetsons say goodbye to their friends, the Flintstones. And Fred echos his famous catchphase "Yabba dabba doo!"
- Jon Bauman - Iggy
- Mel Blanc - Barney Rubble / Dino / Mr. Spacely
- Daws Butler - Elroy Jetson / Cogswell / Henry Orbit
- Hamilton Camp - Turk Tarpit
- Henry Corden - Fred Flintstone / Knight
- Julie Dees - Betty Rubble / Jet Rivers / Investor / Panelist / Harem Girl
- Don Messick - Astro / R.U.D.I / Mac / Announcer / Store Manager / Robot
- George O'Hanlon - George Jetson
- Penny Singleton - Jane Jetson
- Hal Smith - Narrator (impersonating Mr. Pebblehead)
- John Stephenson - Mr. Slate / Moderator / Investor / Poker Player
- Brenda Vaccaro - Didi
- Jean Vander Pyl - Wilma Flintstone / Rosie / Mrs. Spacely
- Janet Waldo - Judy Jetson / Female Computer
- Frank Welker - Dan Rathmoon / Johnny / Mr. Goldbrick
- Patric Zimmerman - additional character voice