This happened at Tokyo Big Sight during a gaming comvention/show. Too many people tried to rush up to the third floor right when it opened. That's actually the Up escalator that's having troubles. Weight limit was too much, so it kicked into reverse.
i was going to make a "zerg rush" joke, but that conjured the image of hundreds of zerglings with convention bags and wearing name-tags tumbling down a escalator.
do they not even understand the concept of turning around and walking off? it's like everyone on the escalator is just looking over their shoulders going "hrunh?" not realizing that's going to be them in a few seconds.