Koji Unoki, who was Yosuke Shima/Dyna Blue in Kagaku Sentai Dynaman, appears in Episode 5 as Officer Hiroshi Tachibana, a policeman who befriends Lou and Sara.
Yoshinori Okamoto, who in this series played Cowler's assistant Bo Gardan, was in Dengeki Sentai Changeman (the previous series as Booba). He also returns in Choujuu Sentai Liveman (along with the actors of Cowler and Wanda) as Doctor Ashura.
What Could Have Been: Titan the Hero was originally planned to be a semi-regular character who would show up once in a while to help out the Flashman team and pilot the Great Titan. Had this been the case, Flashman would've been the first Sentai series to feature an extra hero.