What's a see saw doing in a graveyard in the first place?
LOL - you probably weren't asking seriously, but just in case: it's a makeshift see-saw, a plank upon which a king and queen are (per the Readalong record I had as a kid and still have practically memorized!) "teetering on a gravestone." It's here at roughly the 5:30 mark:
It was one of my favorite images from the book, and one of the things I was most excited to spot in the graveyard when I first visited WDW around age 8.
I do hope every Haunted Mansion lover will check out that little record/book linked above at some point, because it explains a few things guests sometimes misinterpret about the attraction, such as what's happening when you go out the attic window and descend into the graveyard (not leaping to your death, as I've heard many guests inform their companions in hushed whispers, but escaping the attic by climbing out the window onto a balcony, and then down a tree). Of course, at the end of the day, the Haunted Mansion story is whatever each guest imagines and wants it to be, but even as a kid, I guess I was a stickler for interpreting things based on the source material!
I'm excited about the Hatbox ghost addition, but sorry it doesn't look like it will be making an appearance when we visit next week! It may be years before we get back, at which time we'll probably be looking at a B-mode version, "Disco Hatbox Ghost."