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.
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.
Jeff Bergman was used in some scenes, because George O'Hanlon and Mel Blanc died during production. The film is dedicated to the memory of both men.
Hanna-Barbera's casting director, Andrea Romano, requested that her name be removed from the credits after the film's distributor, Universal, made an executive decision to replace actress Janet Waldo with pop singer Tiffany as the voice of Judy Jetson. Romano felt it was "such a mistake on so many levels" and that she "simply couldn't tolerate the decision."