Anyone else remember that old artifact,
Johydee's Mask? Did you know that in fact, it wasn't actually an artifact at all?
Well, sort of.
See, when TSR decided to put out their impressive
Encyclopedia Magica (affiliate link) series, they had to figure out what to do with magic items that had the same name but were different enough from each other that they were effectively separate and distinct items. The solution they came up with was to append them with Roman numerals. So far so good.
But for some reason, in volume two of
Encyclopedia Magica, the entry for
Johydee's Mask from the AD&D 1E DMG (page 158), where it's clearly listed as an artifact alongside the likes of
Heward's Mystical Organ or the
Machine of Lum the Mad, was downgraded to an ordinary magic item. It had XP and GP values and everything (8,000 and 40,000, respectively). It was even listed in the random magic item tables in volume four (Table K), so this was clearly no mistake. Particularly since the AD&D 2E version of
Joydee's Mask, from the
Book of Artifacts (and listed in the EM as
Johydee's Mask II), is still listed as an actual artifact.
Also, for some reason
Encyclopedia Magica volume four only has an entry for the
Wand of Orcus as it appeared in OD&D's
Supplement III: Eldritch Wizardry, omitting the entry given on page 162 of the AD&D 1E DMG. I recall being quite ticked about that when I first noticed it, since I was reading the Planescape mega-adventure
Dead Gods at the time, in which the
Wand of Orcus plays a notable role.