If one watches the morphing sequence of the Rangers, notice where the show producers placed the torso zig-zag pattern in relation to the Rangers' animal symbols in the background... (Hint: The zig-zag forms the teeth.)
Terra Venture's trip itself. Remember that the end of the last season ended with the destruction of the United Alliance Of Evil, and thus the majority of hostile aliens in the universe. If there was ever a time to explore the universe, that seems like a pretty dang good one.
Karone not getting any grief and instead being rather Easily Forgiven for the acts she committed during her stint as Astronema fall under this when one considers that she created the Psycho Rangers, which ultimately led to Kendrix's demise. You'd think the other Rangers would at least find it hard to look her in the eye until you consider that she only created them after Darkonda forcibly reverted her to evil via Unwilling Roboticisation. So technically, it's his fault that Kendrix wound up having to sacrifice herself.
Two apparent fridge logics: where do Psycho Rangers comes from with Dark Specter destroyed? And how can they be destroyed using just two team finishers, while doing so during In Space just turned them to monster form? Actually, these two questions answer each other. They just had some inner power, but no source, so no giant monster form for you, (except for pink, with a new source).
Magna Defender's sacrifice. The guy had his son killed, then was trapped alone below the ground for three thousands years. When he finally gets out, he gets vision of his dead son telling him that he shouldn't be driven by revenge and is still a good person. Good and all, but that ultimately leads him to sacrifice himself to protect innocents while seeing his son telling him how proud he is. Repeat: a guy trapped alone for thousands of years has visions of his dead son which result into him killing himself as a redemption. We thankfully see them as spirits in the next episode, because otherwise, we couldn't have been sure that it didn't all happen in his head.
The ground surrounding the cave where the warrior that Karone turned into stone when she was Astronema is is littered with decaying skeletal corpses, some of them having been impaled with swords or other weapons. That in itself is scary enough, then you ask yourself how they ended up that way and realize that the likeliest answer is literally standing next to Leo. Just to drive this home, one of the skeletons suddenly comes to life and wails that Astronema did this to him while pointing at Karone, thus outing our latest Pink Ranger at this point as a mass murderer. And no, she hadn't been a victim of Unwilling Roboticisation when this happened, either.