Hey OwnedCore, pre apologies if this is a repost or whether it's not classed as an exploit. However, this is one of my first contributions so don't qq.
Earlier today, we began playing BGs and queued for Strand of the Ancients. The Fire Mage we were playing with was originally frost and had a water elemental. Half way through the SoTA (the interval) he changed spec. At first, the water elemental disappeared; however upon respawn, the water elemental also respawned with him.
After the game, the water elemental was still active (including its freeze) outside of the battleground and additionally upon teleporting/using portals/hearth. He then had it in the next battleground too.
The effect was removed when he died outside of a BG. (Obviously without an automatic spirit healer.)
Here he is, a fire mage with a water elemental outside of a BG:
Edit: here's a link to a forum post regarding the same matter last night on US realms.
http://us.battle.net/wow/en/forum/topic/6412104171