I remember once though where I had a dream, then woke up, then like 1 hour later fell back to sleep again, and had the rest of the dream, as though it were on pause since last time I fell asleep.
The two other ones that were close to nightmares was about:
1. I was being chased by minature aliens, and hiding with my friend and sister in a toy factory, manage to evade them long enough, until they had to refuel.
2. All I can remember about this one was finding a dead person I knew from my old tae kwon do class, dead near a stream. Thing is, I don't particularly like him. And I think in the dream I was sad. Of course however, this dream occured not long after my real life friend died.