So I found this thing where sometimes, a normally fatal fall will simply do nothing. I assumed it was lag at first but I never took the damage, as you usually do when it lags.

I have had cases of it in the nether and overworld, and just a note, this is on a third party Minecraft server, so it could just be the server. 

It would play the falling sound, but no hurt sound. It's just a small thing, and might just be the server but I thought it was worth mentioning.