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 at one point of the film. When Judy Jetson and Apollo Blue are in the hologram, and Judy falls through the hologram tree, Apollo asks her if she's alright. Judy responds, "Uh... I think." This line is said by Waldo.