I'm stumped, Laura. I've looked at this 3 times and the best I can come up with is either something in Mousegears or something strange at Rock 'N Roller, though I don't think it's the latter.
I very, very highly doubt it, but it's not a rear engine on that space station thing you ride up past in Space Mountain, is it? You would have had to use the flash to get a picture like that of the station, though...