Kyoryu Grey is Eiji. Interestingly, this applies both in and out of suit, as the suit actor is also the same as Bouken Silver.
Nobu's late brother-in-law is Decade!Kabuto... suddenly being stuck in Clock Up seems better...
And his old friend heading the robotic project in #15 is another Kamen Rider, Ibuki.
For a while now, the ending credits have featured video clips of kids dancing to the tune... and then episode 20 featured one of very much grown-ups "Kenichi" and "Hiroshi" clearly having the time of their lives.
And speaking of Kamen Rider, we have a girl named Yayoi who wears glasses in a Riku Sanjo work. Are we talking about Yayoi Ulshade, the granddaughter of Kyoryu Violet? Or is her name Yayoi Tokuda, the Coma Zodiarts?
The head writer RikuSanjo originally wanted Blue to be a 45-year-old family man. The idea was vetoed, but some elements of it seem to have been used nonetheless in a downplayed form (he's still the oldest on the team at 32, and acts as a surrogate husband and father to his sister and niece respectively), and it was even given a reference in Episode 8 when KyoruyBlue's "old man jokes" cause Yuko to speculate on his age:
Yuko: He might be a hero, but he's got to be at least 40!
Nobu: No way Blue is already 40 years old! He's definitely younger than that. ...I think.
What Measure Is a Non-Badass?: The creator realized that after the majority of the previous series have Yellows who are female (there's only been one male yellow in the last ten years). Predicting that the target audience would consider Kyoryu Yellow too feminine regardless of gender, yellow was ultimately excluded from the main team.