Something I frequently notice in movies and TV shows that is totally unrealistic: two characters having a conversation, or one character doing something, and another character watches, listens, but is otherwise not in view of the others.

In real life, when you are outside doing something, another person can't be 10 metres away and you are not aware of them. People are not that unobservant.

Also, in real life, people do not have a lot of conversations out in public where anyone can listen. Especially super important business conversations.

The worst show for this was Damages - I remember every episode featured like 10 scenes of this.

viz. https://tvtropes.org/pmwiki/pmwiki.php/Main/TreeCover