Yes, I Have Made Unreal 911 Calls
I set my phone to lock after a given amount of time. To unlock the phone you must provide a password or passcode. However, there is a button on the screen to place a 911 call bypassing the unlock. Well, I had the phone in my pocket and was driving around town (in fact it was nearly the same location I made the 911 call yesterday) and the phone rings. I missed the call and picked up the voice mail. It was the 911 dispatcher calling me and stating I had placed a call and they were calling me back to inquire about my status.
Well, I got off the road and tried to reach them via non-emergency number but could not do so. I then called 911 (IIRC) and told them all was fine and I was disabling the lock mode on my phone.
All was well and I have not done anything similar since.