Thanks for clarifying your set-up. That is in fact not a "hashbang" - hashbang is the name given to URLs that use
#! followed by some variables or state. Google actually had algorithms to process those URLs (see the Google Blog) however, that is now deprecated.
For your set-up, I'd call it a "hash key", as usually the
e25500fd is based on the contents of the file (aka a "file hash").
On its own, having the "random letters" in the URL isn't a big problem as long as you have the descriptive part (
aWhiteCat). However, most likely the URLs will change every time the image changes, which means you will end up with several duplicate URLs that resolve to the same image -
That means it will be harder for images to rank in Google Image Search. One image will be seen and ranked in image search, but when the image changes all references to that image will disappear from your site and the new one will appear, meaning Google has to start all over again.
If the images will not change often (or at all) then it shouldn't be an issue.