I've not see any challenger with an integrated mirror turn signal. You'd need the signal wiring to go up there.

That can be rigged but yes, that is possibly a trick of the light.

Yeah, I think the mirror signal is a red herring, it looks like that when viewing on KIA2, but if you right-click and view the image in a new tab, it doesn't really look like that to me at the native resolution of the image, looks more like a reflection.