The first episode, Part One of the Jet Fuel Formula story arc, was recorded in February 1958. However, subsequent episodes were not recorded until February 1959, using a different soundtrack stock. This led to some notable changes in the performances of the voice cast - in Part One of Jet Fuel Formula the clarity of the voice cast is noticeably better than in subsequent episodes, particularly the voice performances of June Foray and Paul Frees; a close listen finds that the studio echo of the session bleeds into the soundtrack. For subsequent episodes the different soundtrack stock used eliminated this echo. In addition, the voice cast's performances began changing, particularly William Conrad's narrations. Throughout Part One, Conrad's narration is totally straight, but in Part Two he began in inject a mild flamboyance to his narration in keeping with the show's whimsical flavor, and as the series continued his narration became ever more comically melodramatic.
Representatives for Red Skelton contacted the producers claiming that Bullwinkle's voice was an unauthorized use of a character voice created and owned by Skelton for his character "Clem Kadiddlehopper". Jay Ward responded by having a segment on the show where Bullwinkle would address the issue . . . in a voice that was a deliberate imitation of Clem Kadiddlehopper.
In one of the various opening title segments which were repeated seemingly at random, Bullwinkle falls past an awning, above which is a banner where the name J. Wa (for Jay Ward) can be clearly seen. The same banner is gone a few seconds later when Rocky is catapulted past the same awning.
On the days when Jay Ward didn't feel particularly creative, he closed up shop and took the whole crew to the racetrack with him This was brought up by a writer from the show in an issue of Writer's Digest.