* HeyItsThatVoice: Jonny was voiced by Tim Matheson (credited as Tim Matthieson), who, besides extensive live-action work in TV and film, would also do voice-work on ''Sinbad, Jr.'', ''WesternAnimation/SpaceGhost'', ''WesternAnimation/BatmanTheAnimatedSeries'', and ''WesternAnimation/TheLegendOfCalamityJane''. The first voice of Dr. Quest was John Stephenson, who did a lot of voice work for Creator/HannaBarbera. The second voice of Dr. Quest was Creator/DonMessick, the voice of [[WesternAnimation/YogiBear Ranger Smith, Boo Boo]], [[WesternAnimation/TheSmurfs Papa Smurf]] and Franchise/ScoobyDoo (and Bandit).[[note]]Most of his voice work was also for Hanna-Barbera, at least until ''WesternAnimation/TinyToonAdventures'' in 1990, where he voiced Hamton Pig.[[/note]]
** In the 1980s series, [[Film/{{Hellboy}} Jeffrey Tambor]] did several voices such as Hard Rock and Dr. Bradshaw in "Deadly Junket", and Dr. Zin in the two TV movies.
** Creator/ScottMenville voiced Jonny in the '80s series, while Creator/RobPaulsen played Hadji.
* TheOtherDarrin: As noted, Don Messick replaced John Stephenson as Dr. Quest.
* WhatCouldHaveBeen: An article in Television Chronicles stated that Hanna-Barbera had planned at least 39 episodes for the '80s run of Jonny Quest. The dismal ratings and negative reaction played a part in the series' cancellation after episode 13.
** Jessie Bradshaw was originally conceived as a character that would appear in a few episodes of the '80s series as a female counterpart to Jonny. When it came down to the actual episodes that were finished, she only appeared in "Deadly Junket". The misconception that she was a regular new addition comes from the writer stating his original plan, as well as fans confusing her with the later Jessie Bannon incarnation.
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