A few moments before his death, George O'Hanlon had recorded all of his dialogue for George Jetson. According to voice director Andrea Romano, O'Hanlon had suffered a second stroke and found it difficult to read and hear and in the end he died in the recording studio doing what he loved.
George O'Hanlon had suffered a stroke, so when he made late The Jetsons (1962) series and the movie, he was practically blind and had very little short term memory. He had to have each line spoken to him so he could repeat it back.
Janet Waldo, voice artist and the original voice of Judy Jetson, recorded the part for this film but was later replaced by then-pop starlet Tiffany. Studio executives hoped Tiffany would attract a younger audience. Ms. Waldo continued (somewhat graciously) to voice the part in subsequent 'Jetsons' productions.
Andrea Romano requested that her name be removed from the credits as casting director after an executive decision at Universal resulted Janet Waldo being replaced as the voice of Judy Jetson by Tiffany. Romano felt it was "such a mistake on so many levels" and that she "simply couldn't tolerate the decision."
Janet Waldo, the original voice of Judy Jetson, can still be heard during a few points in the film. These include: "Way to go, Dad!" (when George announces to his family about being promoted to vice president), "Uh... I think" (when Judy falls through the hologram tree and Apollo Blue asks her if she's alright) and "Yay, Daddy!" (heard twice: the first time after George presses the button to start the plant, and again when George convinces Mr. Spacely to shut down the factory). There's even one unedited line of dialogue by Waldo as Judy, which can be heard off-screen. When the family convinces George that the plant is destroying the Grungees' home, Judy says "It's more than a city. It's their entire world. You're destroying it and them." It is unknown why the particular line by Waldo was left in (either by accident or most likely since the line is spoken off-screen and people would assume that Jane who says this; however, the DVD subtitles clearly confirm it's Judy who says the line).
George O'Hanlon died of a stroke on February 11, 1989 after he finished recording; Andrea Romano later recalled that he could record only an hour at a time due to ill health and had his final stroke while at the studio.
The trivia item below may give away important plot points.
This movie shares a curiously similar story line as the Star Trek: The Original Series episode "Devil in the Dark." In that episode, members of a mining colony meet with constant damage caused by a mysterious being. Though a darker storyline, the crew of the Enterprise realizes that the miners are invading a creature's world and killing her eggs. It is also discovered that the creature is simply being defensive, and is actually a peaceful, logical being. In fact, the creature's behavior is beneficial to the miners, and an arrangement is made for the miner's and the creature and her babies to partner with the workers, so long as each stays out of the other's way. While The Jetsons Movie has a more environmental bent, the end result of each story is that the humans make more money with the help of the indigenous species.