Two things from Giant Robo: The Animation (One of Mitsuteru Yokoyama's works before he died) were mentioned in this series: One is Kenji Murasame, who appeared in Giant Robo: The Animation as a protagonist in the series, but is an antagonist in this series. And another being that robot "roaring" sound that was heard from Tetsujin 28. That sound was also from the robot Giant Robo from Giant Robo: The Animation.