shooting a bow after going to a creative world and setting to survival

I was messing around with shooting bows and I started a creative flat map and after setting up an archery range I set my gamemode to survival and when i shot the bow the arrow would shoot about one block and then act as if it would hit a mob and drop to the ground. The mob that was over 30 blocks away would take damage but not the same damage than from a fully charged bow.

1. Start creative world (maybe flatmap im not sure)
2. take a bow and some arrows
3. set gamemode to survival
4. shoot at a mob in the distance

thanks