I have spent the last few days trying to figure out the ending of Kanon, which may be a waste of time, but the damned show got stuck in my head like an annoying song.
Anyway I have decided that it does play fair with the audience, and it mostly makes sense. I think I have figured out the major puzzles, though other interpretations are possible. I have collected my notes here: Spoiler Notes for Kanon
WARNING: Don’t read this if you haven’t seen the series. This is not intended to make sense to anyone who is not familiar with the story, and reading it before watching the series will almost certainly ruin it for you.