I am indeed claiming that the errors are
invented by the zip utility/operating system you're using!
7zip is intelligent enough to convert the file names for you without freaking out. The file names affected are for the hidden files used by the mac operating system. Since m$ - and apparently winrar - cannot conceive of another os being used, instead of transparently changing the file names affected, they keep telling you 'error, error'.
Using a non-microsoft operating system is not an error, and they shouldn't report it as such. Period.
No idea why winrar created two directories, and filled in the one with the extra underscore. Maybe it's a winrar thing: if it find an error - real or non-m$ ones - it puts stuff in a slightly different directory, to alert you that something is amiss?
With my 'ever-so-lovely' 7zip I can tell there's 2 directories inside the zip file:
Trident_Down_v2.02
_MACOSX
but the trident_down directory name hasn't got any extra/spurious characters. Inside each directory/subdirectory there's a .DS_Store file, inside _MACOSX there's a lot of files starting with '._' nicely tracking the file history of this oxp, which is probably what winrar has been busy 'correcting'.
Allow me to repeat myself once more(4th time lucky?) no matter how much you trust windows/winrar, perfectly valid mac file names are not errors, either zip or otherwise. They should simply not be reported as such. If you feel that strongly about winrar, you should let the winrar developers know, so they can improve on what I've no doubt is a fine windows-only program!