The Sword of Omens is supposed to warn Lion-O when another ThunderCat is in danger. But when the twins and Lynx-O were attacked, the sword did not warn him. Only Cheetara sensed something was wrong with the twins, then Lion-O used sight beyond sight to see the attack going on at the Tower of Omens.
Jaga inadvertantly caused the destruction of his home planet Thundera by casting the sword of Plun-Darr into molten lava on that planet. It was the sword trying to escape that caused Thundera to be destroyed.
Luna: If Tug-Mug and Redeye can't deal with two kids and a blind old geezer, they shouldn't be called Lunataks.
Vultureman: They're not just kids, they're Thunderkids!
Luna: Enough, featherhead! Do it, Tug-Mug. And do it now!
(Believing the Tower of Omens has been left empty by the ThunderCats)
Jackalman: Slithe will want to know what they're up to.
Vultureman: Slithe! That rotten reptilian has had his day. Luna will pay well for this information.
Jackalman: Luna? You're going to side with the Lunataks?!
Vultureman: You bet, scavenger. I'm sick of always being on the losing side.
Jackalman: You're a traitor, Vultureman! A traitor to mutantkind!
Vultureman: Mutantkind has never done anything for me! From now on, I'm going to take care of myself!
Lion-O: No, Jaga, stay to help us. We need you.
Jaga: I cannot help you directly, Lion-O, but think of me and I will always be there to guide you.
(After escaping a trap set by Mumm-Ra in his pyramid)
Panthro: I owe you, Lion-O. And I owe you all an apology. I got us into that mess. I took off after Mumm-Ra like a terrier after a rat. Impulsively. Without thinking. I guess I just lost my temper.
Lion-O: Forget it, Panthro.
Snarf: We all do it sometimes, even us Snarfs.
Panthro: We're coming for you Mumm-Ra, you worthless bundle of bones.
Tygra: It sounds impossible, but it's almost as though Thundera is re-forming.
Lion-O: That's exactly what Lynx-O said.
Wilykat: Boy, that Lynx-O may be blind, but he sure is smart!
Wilykit: Why shouldn't he be smart just because he's blind?
Wilykat: Hey, I didn't mean it like that.
Wilykit: Maybe you should be more careful what you say, Wilykat.
Mumm-Ra: It was the Sword of Plun-Darr that caused the calamity which brought those despicable ThunderCats to Third Earth. For, as it fought to escape its stone tomb, that sword destroyed Thundera.
Ratilla: You better finish me now, Jaga, because if you don't, I will surely return to destroy you and all Thundera. I will have my revenge.
Jaga: The Code of Thundera does not permit me to finish you, Ratilla. You will spend the rest of your days in exile. And as for the sword of Plun-Darr, you will never see it again. I will seal it in the rocks of the deepest canyons of Thundera. Not even the sword of Plun-Darr will escape a tomb of molten rock. Ho!
This is the first episode the Sword of Plun-Darr was mentioned. It is a double bladed sword which the blades ignite with fire to warn of approaching danger and was in the possession of Ratilla when Jaga confiscated it from him on Thundera.
The Treasure of Thundera is first mentioned in the series. The treasure would become the basis for several later episodes. These involved searching for pieces of that treasure.