The most obvious example I could think of, was the Flintstone's "car". Obviously cars didn't exist at the time. (Neither did most of the things in the Flintstone's lives - which I think is the point of the cartoon: "make a 1920's sitcom, but in the stone age".) But the creators wanted cars to be in the story, so the invented a "logical" replacement for one in the setting.
There are other, less direct, examples of this kind of loosely maintaining the setting: such as using a Carrier Pigeon as a text message. I'm not sure if I've ever seen that done in a kid's cartoon, but it just seems like it would have been done at some point; like medieval teenagers talking through bird-notes, and one of the notes reads "LOL". In this kind of example the creator wouldn't even need to recreate a technology that wouldn't exist in the setting, they merely need to show the viewer, in some way, that they are using an obsolete piece of technology that was used in that period in history as a replacement for a more modern one in their story.
So, to summarize my question. Is there a more descriptive term than "symbol/symbolism" for either the act of using old technology as a representation of new technology, or the item itself that represents the new technology in the story?