It was really just these two (with a disclaimer that I am neither a native speaker or familiar at all with Chinese etiquette):

1) 晚輩禮: a junior’s bow (to someone senior), which is how MCS greets Xie Yu, I think as a gesture of respect to someone older.

2) 半禮: literally half bow, I guess? When someone of notable rank acknowledges someone lower or younger than them. This how Xie Yu returns MCS’s bow.