Will putting a mirror in the middle door facing the elevator door affect the neighbors at the side door?

Putting a mirror in front of the elevator in the middle door has no effect on the neighbors next to it. If a door is facing the elevator door, it needs to be solved in Feng Shui. If you don't think it's particularly good to hang a mirror, it may be more helpful for you to go to the Taoist temple and ask another Feng Shui treasure to hang on the elevator door.