I usually only attend Dreamworld so all my experiences are there.
I've been stuck on Wipeout (but who hasn't?) for 15 minutes. That was a fun experience.
Also my first time on TOT2 ended with the car not stopping where it was meant to and ending up near the end of the tunnel. The emergency brakes kicked in (thankfully) and it took about 20 minutes to get us back to the entry/exit spot. Because I hadn't been on TOT2 yet (had been on TOT1), I thought this was normal, until they let us know we had missed our braking point.
Got stuck on the rapids once as well. Right at the end where the conveyor belt think takes you back to the start, our raft wouldn't lock in and we were stuck at the bottom of the conveyor belt. It wasn't until the next raft came along that we got knocked onto the conveyor belt. The operators had a puzzled look on their face when they saw two rafts come up at once. I think I recorded that moment on my phone as well.