The first Super Sentai series to feature the rangers fighting against evil rangers. (edit/ additional information.) In Zyurangers previous to this, the rangers did fight evil rangers, but technically those were mirage golems made by Dora Mirage, so they were not considered real rangers)
The mask designs of the Doro-Doro foot soldiers are based on Edvard Munch's famous painting "The Scream" (which also inspired the design of the masked killer Ghostface in the "Scream" slasher film series).
The first Super Sentai series to have an extra hero, NinjaMan.
The first sentai series to feature one of the members speaking English instead of Japanese.
Wasn't officially released in the US until 22 years after it first aired in Japan.