Spectator gamemode FREAKING OUT

I was testing out the new snapshot and all the cool stuff in it, including spectoator mode. When I went underground to find a cave, I found one and decided to go to survival mode in it. When I did /gamemode s, the world FLIPPED OUT. It started glitching so much I couldn't get so had to /kill. When I respawned the world was as you see in the attachment.