The workaround, if this happens, is to right-click anywhere on the screen and the cursor will come back. To fix, go into your mouse cursor settings and set to default settings. It most often happens if you have mouse trails enabled, but different mouse themes can sometimes make it occur, too.
I had this happen to me a few months back, which was strange, since I think they fixed it. I didn't have any changes in my mouse settings, but I changed to a theme and then changed back to default, rebooted my computer, and haven't had the problem any more. You could try a "repair game" if it keeps happening. (right-click on the SimCity icon in Origin, choose Repair Game)