After Mark is knocked he didn't notice something is missing from his body.
Ken says "let's return to our seats."
Because Ken is the last person using the washroom, while Mark waits for him outside the washroom no one else notices who knocks on Mark.
The rest of the people just doing their things.
Mark is slightly in pain but since he is a doctor there is some painkiller in his bag.
Mark returns to his seat and opens his bag. Looking for a painkiller. He swallows the medication.
Mark rolls up his sleeves and realizes there is some bruise on his arm.
Ken noticed Mark rolling up his sleeve but he thought maybe Mark is hot. But he didn't realize Mark is injured.
Remy is busy planning what he should do with Mike.
Mike is very busy looking at the Tablet and thinking about what he should speak about during the meeting and it can boost his confidence to get the deal.
Jin is busy watching his movie so he doesn't care what happens to others unless they shout for help.