Why did he act so frazzled when Moriarty said he picked the perfect place to do it? And he was all “Do it? Do… do what?” He obviously knew and it is not like him to be frazzled.
Why wouldn’t Sherlock check his phone in the beginning when he always answers texts immediately?
When he found the camera in 221B, why did he look so sad about it when John wasn’t looking? Also, why did his own image come up on his computer when he was holding it?
What is the point of IOU and is it connected to John saying “I owe you so much?”
Why is nothing ever said about the body of Moriarty being found?
And, somebody already addressed the fact that Sherlock was hyperventilating on the roof and that could have been significant and even helped save him. It’s quite unlike him.