Can a facial injury after Botox cause facial droop?

I think it is unlikely that your fall will affect your Botox and cause any kind of droop but only time will tell.  For now, be patient and kind to yourself as your body heals. It takes about 2 weeks for your Botox results so you should know if there's been any damage by then. Best of luck. 

This is unlikely. It is too early to say what your response will be to the Botox. Final results are usually apparent at 2 weeks. Facial "drooping" would result from paralysis of one of the branches of the facial motor nerves. Bruising does not generally cause nerve paralysis. Good luck to you!