I.... THINK... that those spots are artifacts from picture-merging and are in fact rain droplets on the camera bubble dome thing on top of the van?
When you do look up, it looks like the UFOs are behind the powerlines, which would make my explanation invalid - but you do see some really weird computer decisions when merging issues. (I do a fair amount of photo-merging combining multiple stacks of images taken through a microscope, and there have been times when Z-plane artifacts like this are incorporated, like if the droplet wasn't there for one shot but was for another shot, then the two got merged. Just a /guess though.
Man, that was really awesome to look up and see those, though. A real "WTF" moment, especially on the randomly funny pictures of the LARPers... haha