The bar radical, 㦮, as seen in kanji like 残 and 浅, has the mnemonic “There are two drunkards here. That makes this radical a bar. Where else are you gonna drink?”
I assumed this was somehow referring to the fact that it’s the drunkard radical (戈) with a couple of added strokes, but, reading through the Wikipedia article on Shinjitai, I just found out that it used to be written differently: 戔. In this form, the mnemonic makes much more sense: It’s simply the drunkard radical, twice!
So that makes me wonder, does the mnemonic refer to the Kyūjitai way of writing this radical?
It seems like the underlying cause of this shouldn’t be an encoding issue, since the radical is an image in Wanikani rather than a Unicode character, but who knows.