There is a hole near my cheek and retromolar trigone after wisdom teeth extraction? Is that normal?

Hello, 
This is very common with wisdom tooth extraction. Nothing to worry, it will heal up in some days only. Just maintain your oral hygiene properly.  If there is any pain or swelling is associated with this, then you have to consult your dentist once.

For total wound closure it could take upto 3 to 4 weeks. As long as there is no discomfort you don't have to worry at all. It appears perfectly a normal healing