Well, it wouldn't the first time that a reference was made about something that happened in an earlier chapter, which I missed or simply forgotten about.
Also, sometimes I just want to reread Kuroyan's Gamera reaction.

> and in the later case it's easy to find the first image of the latest chapter, especially if you just unpacked it before reading.

I suppose you could copypaste the filename of the first file... still seems rather farfetched to me, considering I have yet to see why one would unpack it in the first place... well, unless you use a program not made for reading comics for reading comics, in which case, like you said earlier, you'd have to switch zip-files everytime you finish a chapter.