Even though all the projectors on this list are designed to be used outside, it does not mean they can’t be used inside. Yes, it has been claimed a few times that some are too bright for indoor use but if they are not, they can easily be utilized indoors as well. Some people will prefer mounting their projector on the ceiling to provide a good angle for the lens and to place it in a safe location. So, yes, you can mount a projector on the ceiling granted there is a mount on the bottom.
If there is, you could buy a mounting pole and utilize that mounting hole. Of course, you could also simply build a shelf from your ceiling allowing the projector to sit comfortably and safely on it. Either way, it can be achieved if you desire.