Funny and amusing situations...

It’s not funny, but strange: after looking at a screenshot taken the other day from a map I was playing, I noticed something incomprehensible (a bug?), which I had never seen before. There are 5 players on the map: blue, brown, orange, purple, and pink. And in the thieves’ guild, I suddenly see a green flag. But there is definitely no green player on the map; I checked it in the editor. What kind of magic is this? The bug is observed both with the HD mod and in the Complete Collection.
If anyone is interested, I have a save file from that day.