There are instances of unusual happenings in a classroom in one of the SMK St. Columba classroom blocks (Block C, Classroom 4E4), where the lights and the fans would switch on without anyone inside the classroom and when the block was completely locked.
Such an "unusual case" also happened when Wong was in a Prefect camp there.
Wong was doing his duty rounds taking care of the Prefect Juniors in the opposite block, when he saw his friend in that very classroom. However, when Wong called his friend's name, "his friend" didn't answer..
Wong then walked further down, and he saw the same friend in the School Hall..
"But here's the catch: the Hall is more than 200 meters from that very classroom, and it would have taken more than 3 minutes to reach the School Hall...
And it was impossible for him to have ran towards the Hall when the block was fully locked up.