delwood: Weekday and Sunday story arcs are more often unrelated than related. Cartoonists typically draw them as separate projects. What we will expect here is the resurrection of PHB for some reason we simply haven't seen yet. (And I suspect it will be even more suspended belief than him crawling into the duct work. Maybe Ratbert is in there feeding him.)
In British English carcase and carcass are both acceptable spellings, but American English only has the latter. I'm British and I would spell it carcass not carcase, probably because the latter reads 'car case'.