It's kinda rare to have an inactive mob stored in another map, usually it's on the same one.
Doom Eternal speedruns, on the "big gun" map, store some assets in a secret room off-map (with a different skybox). One of the main skips is to clip out of bounds, and get to one of these debug rooms.
I think the same is true for some Ocarina of Time "any room" skips, used to get into/out of the Great Deku Tree and fight that Young Link boss. Or warp straight to the ending escape sequence (post-boss).
I think the entire world here is the same "map". Since she fell down through the "Heaven" sky and landed there. Probably just faster to take the warp to get back, rather than runback.
Oh, one last one, a lot of Souls games have this. I think Elden ring? You kill one boss in the sky then plunge attack his body down through the clouds as he falls, as the bottom map renders. 2 minutes straight of falling.
Boss dies on ground impact due to massive fall, and starts animating death scene, but player falling following him attack "lands", to take no player falling damage. I forgot which game/boss exactly.