One person "remembers" that scene based on decades-olds memories conflating deleted-scene-pics, parts from the comic or novel, or just plum made up (I mean, Lando had to go out there and get Luke, so it's natural to imagine how that would have gone).
Then, based on the suggestion from that one guy, it triggers or creates the same phenomena in others.
It actually happens all the time.
Notice it's "when I saw it in the theater" (thirty-one years ago!) or "on TV when I was five or six". Or they had it on tape but haven't seen the tape in twenty years. Always, without fail. It's always some vague half-remembered thing from early childhood or from so long ago that most of the people reading the posts weren't even alive yet. This is no coincidence.