ADVISE!!

I have a 5 month old golden retriever puppy, I got him when he turned 3 months old. He does EXTREMELY well with commands, such as no, sit, shake, and lay... the problem is accidents inside, I will watch him with my own eyes go potty out side and then when he comes right inside he will go again like he has an uncontrolled bladder? I’m not sure what to do. Any advice? Enjoy this cute pic.