One of the more subtle pieces of worldbuilding that Jodorowsky threw into the mix was the idea that the present characters are living in an environment previously inhabited by giants. It was never mentioned in the text, but there are various visual references throughout.

Here, a local power has built a castle on top of a candle without realizing that’s what they were doing. When they activated a power source on the wick, the entire castle exploded and melted away. What’s wonderful is that we just have these two panels that tell us that’s what’s happening.

(Heavy Metal issue #105, December 1985 – Page 36 The Jealous God by Jodorowsky and Cadelo)