Say, does unfinished continued stories count as Mopees? Then how about Metamorpho being wanted for the murder of Saphire Stagg's husband and going on the run with Element Girl Urana Blackwell in the final issue of Metamorpho? Or the Metal Men being made into, essentially, androids in the last five issues of Metal Men, only to reappear as robots when they refurfaced in Brave and the Bold?
If I remember right, there were explanations given during the Steve Gerber run for why the Metal Men lost their "human" identities that were given later on (and for why Professor Magnus returned to normal), so it isn't a "Mopee" story if it's explained away; only if it is just never mentioned again.
While DC loves top make huge deals out of re-cons and restarts these days to boost sales, back in the Golden, Silver, and Bronze Ages it seem to happen all the time!
Lots of good ones:
The 1st Krptonite ever seen in the comics was colored Red, not Green! This version of Red K was re-Con into Green K, later another completely different Red K appeared which we all know and love.
Originally, The people of Krypton were called Krptonites! Later this was re-con by renaming them Kryptonians.
Superboy was never part of the mainstream continuity until many years after his comic was released, it wasn't until well into the 1960's that Superman's origin finally included him, thus making him official.
Speaking of Superboy, his comics re-con countless things, mostly people meeting a lot sooner than what was written in the Superman comics.
Some of Superman's powers was re-con in and out of continuity depending on the story.
Sandman saga anyone?
The list is endless..
I don't think you're entirely clear on what a "Mopee" story is. A "Mopee" story is a tale that promises to make an extraordinary, earth-shattering revalation that totally recontextualizes something really important about a character, a revalation that is never, ever brought up afterward because everybody agrees never to mention it again: e.g. that the Flash's speed comes from a magical little elf, or Batman had a brother.
A few bumps and glitches in a character, particularly at the beginning (Daredevil using gadgets in his mask, Professor X admitting in a thought bubble that he "loves" Jean Grey, Superman using telepathy, the Fantastic Four living in a fictional city instead of the Big Apple, Batman using a gun, Dr. Don Blake building an android) are just that: bumps and glitches, more common back in the day when only guys like Roy Thomas and E. Nelson Bridwell were keeping track of these things.
(Also, it should be noted that "retcon," as Roy Thomas originally defined it, had a much more specific meaning than how it is used today.)