It looks like common depictions of the Tower of Babel and considering it leads to the Sky Castle, it probably is based on it. I'm also suspicious that a robot falling from a castle in the sky was inspired by a such a scene from Miyazaki's Castle in the Sky.
This picture was basically a send-up of those "Video Game Design Facts!" posts on tumblr, which always strike me as being incredibly smug. Most of my earlier Made Up Facts were meant to be plausible, this one was more giving back the "I know something you don't know, nyeh nyeh" vibe :)
Given that tumblr took over from myspace in the "here's my profile/homepage, it's full of animated .GIFs" department, it's surprising that some users take the time to read game's wiki-s. I guess I'm saying I'm not really holding my breath for tumblr investigative reporting, involving interviews with game developers.