I'll let Nick explain it, "But here's the thing: the note was never written. Ray gets it from Gaelon and gives it to Young!Gaelon, creating a theoretically stable time-loop, except that at no point did anyone ever actually write the note."
All it would have needed was a single scene where Ray writes the note, but we didn't get it, so the time paradox remains!
Thanks to Nick for the fascinating (if obscure) suggestion!
If anyone else can think of a good inexplicable comic book plot, write me at email@example.com!