Episode #1.9 - S1-E9
Continuity mistake: After Kang-bae takes off the sunglasses in the parking lot, he asks Yeo-rin "what are you doing here", then it cuts to an angle with Kang-bae's back to the camera. His right hand can be seen at his side, doing nothing. But in the next shot, it is suddenly in his pocket, putting the sunglasses away. (00:06:28)