I found some kind of bug with Kibana 5.1.1 and FireFox.
When I go to "discover" and click on the small arrow to extend the found results, I'm getting the error:
NetworkError: Failed to load worker script at blob:https://myserver/e24df2a1-7e28-48f3-998b-258034fdbdaa (nsresult = 0x805e0006) (:0)
This only occurs with FireFox (version 51.0), Chrome works perfectly fine.
I tried to set CHMOD 644 on the worker-json.js as mentioned in https://github.com/elastic/kibana/issues/3610
but that didn't help.