I learned that Perseus had one accent as a child, and a completely different accent as an adult. And as far as I could tell, neither of which sounded like either of his parents.
I also learned that Bubo (aka the mechanical owl) was my favorite character in the original, and it just isn't Clash of the Titans without him. Granted, I was a big fan of that movie as a child, so this may be nostalgia talking. I really need to get a hold of a copy of that movie and watch it again.
If nothing else though I can safely say the music in the original, was much more memorable. I can remember music from the original even today, having not seen it in at least 15 years. But I saw the remake for the fourth time today and I can't recall a single bar.
Speaking of the Stygian Witches, as I just was in another topic; I learned they're all knowing and/or all seeing, yet they don't have enough sense to not throw their only source of vision (real or supernatural) to one of their sisters who happens to be within one foot of the resident demigod, for no apparent reason.