[Kaixa]

All of the monsters in Boukenger are actually based on the mecha of all of the previous seasons, and all of the rangers were based on rangers from previous sentai series. Also at the end of the episodes after the ending songs, they do a recap/highlights of previous seasons, so it definitely was intentionally made as an anniversary series.

Ohranger was also originally planned to pay tribute to Super Sentai's roots and actually started off that way by having a serious tone akin to Gorenger. It even had Hiroshi Miyauchi, the original actor who portrayed Aorenger and Big One, as the mentor for the team, but the production staff felt obliged to rewrite the story mid-series to make it lighter and less serious due to a massive earthquake causing serious casualties in Japan.