@Tim_G The third person would but they know that would be frowned upon for interrupting the meeting.....

Yes they control the meeting. Yes they are in a position to communicate from it. Yes the third person does have insight into the meeting.

This is a general question. If your department consists of three people. Two of them go into a meeting. Leaving the third one to cover the department. Then the third one is suppose to be off at a certain time but their meeting goes over, and no one tells the third person anything. Leaving the third person to cover the department past their clocking out time, is that rude? Also the third person has recently acquired a temporary medical condition that wears them out during the day.