Milestone Celebration - This series was made during Kamen Rider's 30th anniversary and contain homages to past Kamen Rider Series. Some of the monsters are based on old villain's, and you can make the case the lead riders themselves are based on previous Kamen Riders. It also homages the Metal Heroes series which Kamen Rider took the place of and incorporated some concepts.
Older Than They Think: While Tackle's status as a Kamen Rider continues to be debated upon, Femme is not the first female to be shown transforming into an undeniable Kamen Rider form, and Shuki isn't the first female Rider either on TV. Both of those honors go to Yukina Sawaki, Shouichi's older sister and the first Agito, who is even shown in a flashback to (unwillingly and painfully) transform into Agito Ground Form. While she did not become an active Rider like her brother or her more well known successors did, this is still an undeniable case of the first female Kamen Rider, at least within the Heisei Era