7 Totally Accidental Wrestling Title Changes
7. Thea Hail Wins The NXT North American Championship

Thea Hail's victory over Blake Monroe on the December 16th edition of NXT would have been an excellent bit of business had absolutely any of it been a work.
As NXT booker, Shawn Michaels has crafted a shock title change or two in the past, and in doing so has at least created the in-universe rule that the unexpected can happen on the right night in the right moment with the right wrestlers.
This was literally none of the above.
Relatively early into the action, Hail attempted a springboard Coffin Drop/Trust Fall onto Monroe, who seemed to fail to crucifix her for a counter. Hail slid forward, the referee counted the fall, and kept counting to three without evidence of a visible kick-out from the Champion.
Having not been booked to win, Hail didn't really know what to do in the moment. Having not been booked to lose and lose her title at that, Monroe was even more unsure. As the referee scrambled to communicate the events to the wrestlers and ring announcer Mike Rome, somebody backstage played Monroe's music, presumably because it was cued up to go in line with the original finish. At this point, the wrestlers were at least locked in to their sudden new sell-jobs, but Rome misspoke too, announcing Hail as the World Champion rather than announcing the secondary strap.
A mess, but one the booking could move to clean up once people had stopped making fun of it. Such is the nature of live TV, as opposed to taking place under the former veil of secrecy that was the house show loop...