1. Stunt/ World Record attempts gone wrong,
2. Gone from road to off road at high speeds, because someone was driving more towards the wrong side (esp. on narrow roads)
3. Cornering mishaps (ran too wide, leaned too much, lost the front end, etc.)
4. Crashed with oncoming traffic while overtaking,
5. Obstacles coming in way (cow, dog, pigs, pedestrians, etc.)
6. Nervous or uncooperative Pillion causing an inbalance,
7. Mechanical Failure, Punctures, etc.
8. Changing lanes without care or without seeing RVM's,
9. Road Rash,
10. Something else crashing into stationary vehicle, like a bike stalled in middle of train tracks, parking lot crash, etc.
11. 3 way/ 4 way Crossing: Mistake of anticipation (who goes through first, etc.)
12. Losing grip while braking/ acceleration,
13. Taking a right hand corner directly, without going circling the chowk/ circle, etc.

Are there any more possible scenarios?

Here in Pune, one of the deadliest city in the world to ride, you will often find roads disappearing, dim signals, only one signal light pole present and it's hidden somewhere, huge speed-breakers, so huge even bigger sedans like merc have all wheels on the same speed breaker at the same time, built by military, etc,. Basically govt bodies try to rip you apart in order to keep that 'deadliest' title intact.