Concrete Revolutio

Jiro Hitoyoshi's character is a throwback to Jiro, the main protagonist of Kikaider. Not only do they share names, but in episode 3, he's seen playing an acoustic guitar, which is what Jiro from Kikaider is always seen carrying on his back. Jiro Hitoyoshi is also seen playing guitar on the album cover of Concrete Revolutio's soundtrack.

The first ending theme of the series has a lot of surrealist imagery. In particular when they show Fuurota's title screen, there's a picture of a man's face in the background, presumably one of the staff members on the show.