The original"Devilman" series plays on the TV when Akira remembers parts of his childhood. A still image from that same series also comes up when Taro searches for the Devilman online.
Director Masaaki Yuasa is a fan of Gô Nagai's "Devilman" manga comic, and was pleased to have the opportunity to adapt his favourite work.
Masaaki Yuasa adapted Gô Nagai's "Devilman" saga with the understanding that Nagai was probably restrained in the depiction of its sexual/violence by the story appearing in a 1970s kids' manga and TV show. Yuasa felt that Nagai's later works were much more extreme, and so he created Crybaby with the mindset of "Nagai-sensei could have gone this far if he'd done as he pleased".
Miko Kuroda's design after merging with a demon bears a strong resemblance to Riki Muso, a character that appears in Shuten Douji and Violence Jack (both of which were also created by Go Nagai), and it's possible her design served as an inspiration for the look of Miko after she merged with the demon.
Gô Nagai: Creator of the "Devilman" manga, appears as a member of the lynch mob in Come, Akira (2018) and Go to Hell, You Mortals (2018).