The bug:

Just a small bug concerning the chunks;

I happened to be mining deep and randomly underneath the surface of a default world, until I noticed that when looking around for ores to mine in F5 mode (default key to 3rd person view); the long corridor of mined blocks behind me had become transparent, and were considered as air blocks as if I was in Spectator mode... but wasn't. Pretty useful for locating caves I guess...

However, once I returned to first person view everything went back to normal (as if nothing happened). This can be done in Survival, as well as in Creative mode.

How to reproduce:

• Create a new world (I created a Superflat world)
• Start mining a 1x1 hole at a random location as far from the surface as possible
• Then start mining in F5 mode... (follow the screenshots)
• At some point, you may notice that everything behind you becomes transparent..

Please let me know if this is a bug and thanks for your time!

Here are some screenshots of what I think is a bug: