Updated with a preview of the event! =)
Apparently it was badly affected due to an unexpected heavy snowfall in the Jamsil, Seoul area.
The heavy and unexpected snowfall left most of the idol and filming crew stuck in traffic, delaying the whole process. Furthermore, outdoor track events like the 100m dash that was to be filmed at the Jamsil Olympic Main Stadium had to be replaced with a 50m indoor dash at the nearby Jamsil Gymnasium.
Some photos with regards to the event has been released! Check it out at here! (Warning: Heavy spoilers)