I hope this hasn't been brought up before, and if so, my apologies.
Anyway, I was on Online (in the browser version of the game) and it was a 1V1 match with Vampire on and 3 stock with no time limit. I selected Emerald Cave as the stage and when the game loaded, there was no Sandbag training: instead, it was me, Ichigo, against my opponent, Marth, fighting on the Waiting Room stage. I mean this wasn't a CPU glitch or whatever, the dude was in full and complete control the entire time. He attacked me intelligently, I attacked him back and we attempted to recover after getting knocked off stage. We actually spent the first few minutes just standing around and taunting, trying to figure out what the heck happened XD. I ended up winning the game, and immediately after so we were disconnected.
I managed to print screen an image of this happening and it is here below:
^Basically it's an image of my opponent dropping back onto the stage after I got rid of his first stock. Not much to see I know, I should've captured a moment when we were in battle, but before I thought of it the game was over.
Overall, awesome experience, but I don't think it's supposed to happen.
Unless this was a test and Waiting Room's gonna be a stage once again in Beta.