That's an Adobe shockwave file. Maybe people searching through Adobe have been looking for it, and gave it page rank.
Amazing... I m not sure There was some rumors about that flash SEO (http://www.hochmanconsultants.com/articles/seo-friendly-flash.shtml)
This is interesting. Could you please share a link? I would like to try to analyze it and see how they got PR for a SWF file!
This is the link, I've tried to test it on PR validation sites, but it doesn't work. But Google toolbar shows it as PR2: http://aolsvc.aol.com/onlinegames/goldminervegas/GMVegas_Web_AOL_LIVE.swf
flash files, and its content also index by Google. So, they will consider as normal html pages and if the flash files have good content then they also get into the serp. If they have good backlinks, it gets good PR.
Pagerank applies to all URL's. If that SWF file had several inbound links then, yes, it's possible to have a PR.
Yes, it can apply to images too, if you get backlinks to the image's URL directly, and not to the page where they are displayed. This is unlikely to happen in practise, but who knows.