Gustav's character design was reused and outfitted with a beard for the character Uncle Oscar in the series Legacy from the Future - Fantastic Adventures of Family Mézga (1970). Both were even voiced by the same person, Alfonzó.
The series was considered to be adapted into the first feature-length Hungarian animated picture as early as the '60s. One idea was to just play all the shorts, linked together with newly animated scenes. Another concept that got thrown around involved Gustav traveling through and spoofing Hungarian motion picture history. In the end, all ideas fell through due to financial limitations and creative differences, and Johnny Corncob (1973) became the first Hungarian feature-length cartoon.
Early episodes used very exaggerated, cartoonish designs and a thick-line animation style reminiscent of the American UPA cartoons. Gustav had a head bigger than his body with large eyes. Gradually, the art shifted, adopted thin outlines and a vaguely more grotesque style, with Gustav having more realistic proportions and small, beady eyes.
Most of the creators reportedly did not take pride in working on the series; they said they were not making art, just doing "menial exercise". Co-creator and animator Marcell Jankovics did not enjoy the series' comedy, as it targeted and made fun of the lives of everyday people, who were under a lot of stress under the Communist rule anyway. His proposals for an episode in which Gustav is a high ranking official were even turned down. He began to like the series even less when one of his friends asked if he was still working on that "silly thing". After this comment, Jankovics began to take animation as an art form more seriously, and he would make less comical cartoons.
There are two urban legends about the origin of Gusztáv's name. One has it that he was named after the godfather of co-creator Attila Dargay. Marcell Jankovics however claims Dargay randomly pointed at a name in a telephone book, and picked Gusztáv because one of his music composer friends had the same name. Jankovics supported the choice because in Hungary, Marcell and Gusztáv share the same Name Day.