Interesting thread, a similar thing happened this summer when I was trying to get from HKG to FRA, flying LH. I was upstairs in F on the 747 and while still at the gate, with everyone seated, the captain came on the PA and said there was some severe weather conditions over mainland China preventing us from taking off. So we had to wait for 1h 45m.

And then.

We start pushback, clear the gate by a few feet and... the plane stops. After a few moments we start moving forward and outside I can see them scrambling to get the gate back into position. Captain gets back on the PA and yep, turns out there was a fist fight in economy class. Me and the guy across the aisle shared a funny look at that point, and I later asked the purser what happened. Well, one guy reclined his seat, the guy behind wasn't too happy and... boom.

So they had to get those two guys off the plane, authorities waiting, and then unload their bags. By then we were a few hours behind schedule and as it turned out, we weren't quite done with the action just yet. A distinct smell entered the cabin. Fuel. Crap. Unidentified leak. That got everyone a bit tense. FAs were told to be in standby for immediate evacuation, firetrucks came, but after 30 min or so they determined the leak wasn't us.

So, fourth attempt to get going. But no. One of the engines wouldn't start. We were stuck. Again. And they had no clue how long it would take for them to have it fixed. Any chance of catching my connecting flight out of FRA was long gone so I asked if I could deplane and be rebooked onto the next day's flight. The FAs said sure and I was escorted back to landside while they dug my bags out. Kind of fun to have them delivered back to me on a special, tiny luggage belt.

So anyway, I ended up getting another night at the Hyatt and had a really nice ferry tour of Victoria Harbor. Thanks to some fistfighting guys in economy.