UPDATED OCTOBER 23, 2009 9PM EST
Blood
Super Sentai has a lot of blood and blood has been skimmed through by Power Rangers. It hasn't been addressed or referenced to, until RPM. For Tenaya to discover she is not a robot, she has a injury and sees blood. The Rangers have gotten scrapes and bruises before, but not as much as this. Kenny reminded me that we saw Zenaku/Merrick's blood in Wild Force.


Multiple Supporting Character DeathsEven though Master Mao died in the beginning of Jungle Fury, it wasn't directly said he 'died,' only that he went to another plane of existence, more specifically, the Spirit World. But it has been stated time and time again that Scott's brother Marcus had died during fighting Venjix. Also, Summer's butler Andrews had died. Gem and Gema were believed to be dead by Dr. K, but of course turned out not to be, much like Mike and Kendrix of Lost Galaxy. So characters had died before but they hadn't stayed dead. It is also the first to mention 'death' so often, like in "Ranger Blue" when the little girl asked Flynn "Are we going to die today?"
The most zords in one Megazord or UltrazordThe RPM Ultrazord is the first to have twelve zords in one.
This part was Updated 10/19/09 7:15 pm estAnd a kindly reader reminded me ever so nicely....

Organized CrimeIt is the first season and maybe the last to ever cover the mob, a.k.a. organized crime. They have not specifically said 'mob' but the Scorpion Cartel is most obviously a mob, I mean they use the word 'cartel' for godsake. And they use the slang term 'ghost' instead of kill or mob hit.
Rangers to be ImprisonedThe first season ever to have Rangers in orange jumpsuits, basically incarcerated Power Rangers. It was only for two episodes: Fade to Black and Ranger Green, where Ziggy returns to jail thanks to Dr. K believing he betrayed their trust.

HolocaustThe definition
is destruction or slaughter on a mass scale, esp. caused by fire or nuclear war. So it is a holocaust. It is the only season to cover total annihilation for a long period of time, it is the main theme basically. No real lush green fields of New Zealand in this season.