For more evidence that this is indeed just an optical effect, check out this video that @Bam posted of a bat in his garage. There’s a light trail visible behind the bat that’s basically just the outline of the bat’s body. Since it’s coming toward the camera, the trail isn’t as visible as in this situation, where it goes across the camera plane at roughly the same distance the whole time, and at extremely close range. But it’s the same idea. You’re looking at one bat, not three bats.
