Mark's watch reveals that he enters Lumon on the 4th day of the month. Later that same day, when Mark leaves Lumon, the date on his watch now shows it's the 5th, and the crown on his watch is unscrewed.
When Helly is locked in the conference room, she attempts to turn the door lever several times, but it doesn't move. Later, when the door is seen from the other side, the lever is moving up and down (the door being secured only by a deadbolt).
The instructions state that the candidate has to ask three times to leave in order to be allowed to exit the room. Between Helly waking up on the table and the moment Mark instructing her to ask one more time to leave, she had already asked four times to be allowed to leave, in the forms of "Let me out" or "Let me out of here".