Okay...so fandom, of course, wants answers. So what do we do? Over analyse things. BUT OMG THIS COULD BE A THING
Xehanort playing the 13 darknesses
ERAQUS PLAYING THE 13 LIGHTS (even though there's supposed to be 7, I dunno how fandom explains that)
Possible wayfinder, Mickey head, Sora crown, Ventus shirt symbol, Riku's keychain on his keyblade, Ansem's Guardian's head, Broken Vanitus symbol, and I don't think that's a note (it's not as far as I can tell, maybe an hourglass) Saix for the moon, Vanitas's symbol split in half, Luxord's cards, YMX is Young Master Xehanort, Master Xehanort, Sora's Crown, Riku's keychain symbol,
Mickey's head, possible Axel charm, possible bell tower,
paopu fruit for Kairi (or maybe a little charm that she gave Sora in kh1), Xigbar/Braig's guns.