When there are a lot of members in a K-Pop group like EXO, one of the members is bound to be left behind at one point or another. Poor Kai experienced utter abandonment from the members, who mistakenly believed that he had gotten on the van when in fact, he hadn't. 

This embarrassing tale--well, mostly embarrassing for the EXO members excluding Kai--came to light on the February 24 episode of 'Radio Star' when Chen was asked by the MCs if there is anything difficult about having so many members in a group. 

Chen answered, "It's hard to check the headcount because there are so many of us," going on to tell the embarrassing tale of forgetting a member, namely Kai, in the past. Chen said, "We even left behind Kai one time. Because there were many cars we all thought he must have gotten on one of the other cars." Well...that must have really for Kai. Imagine how bad he must have felt to be left behind by everyone. 

At Chen's confession, Kyuhyun added, "We've left behind Shindong before. At the time, he ran after [the car] like crazy." 

Kai be like:

and Suho be like:

"I feel like I'm forgetting something.. did I leave the stove on..?"