15They're naked in the pilot
The show's creators-- and the ThunderCats themselves-- really let it all hang out there for the first episode of the series. When we're first introduced to the eponymous characters, they're watching their home planet of Thundera being destroyed from the safety of their spaceship… all while standing around in
the nude. You might think: oh, maybe they just didn't have time to suit up prior to evacuation. In which case you'd be wrong. It appears as though Thunderians weren't accustomed to wearing clothing, and their planet may well have been a nudist colony prior to its explosion. We'll never know.
What we do know is that the ThunderCats are quickly equipped with new uniforms and weapons to better prepare for whatever dangers await them on Third Earth. Thus, they don't stay naked for long. But since the ThunderCats action figures didn't have removable clothing, at least we never had to wonder what was going on underneath those uniforms.