We were there that night also, and were routed thru the back way for our exit. I had been back there before on the KTTK tour, but my husband and kids thought it was super cool to be behind the scenes at the MK.
We had pretty much the same reaction. I had been backstage before (KTTK tour) but Dh thought it was pretty cool and we were both really grateful that we didn't have to fight the crowds on Main Street. DS didn't even notice that we were backstage (it was dark and he's only 4). We ended up leaving while Wishes was still going on, took the backstage exit, and grabbed the first bus back to the resort.