I still feel like I remember distinctly seeing an unlicensed port of The Mask from SNES to the NES. Not a cart for sale but rather screenshots obviously captured from a TV and put on some website. Even CaH4e3 once had this game on his wanted list at the front page of his site. But I've looked at archive.org captures of all the old sites I visited back in the day that covered pirates (namely NESWorld) and have found nothing.
Of course, some might be aware that a common FC pirate of the NES game Kick Master has The Mask on the label despite having nothing to do with the game, so I'm guessing I saw that years back and somehow made up a whole port existing. But it doesn't explain my memory of seeing the screenshots of the game having been backported to NES. I still remember one shot in my mind of the Mask doing some move that makes one of his ears become big, or he's honking a huge horn, I can't remember which.
I feel like this is a mystery for FC pirate collectors as Shazaam is for people who remember the 90s. I swear I saw it and yet there's no evidence of it out there. So far my only backup is the fact that Cah4e3 was looking for it at one point, so I can't be dreaming, can I?