Celtics sure showed chemistry issues Opening Night '07-08. 
Then again it was against the Wizards.
I think Miami is getting unfairly criticized for one game. However, I think Miami is going to have more chemistry issues than us.
I think selfishness could be an issue and I think meshing games/getting used to not having the ball is going to be an issue. The question with the latter is if it can ever be overcome. And I wouldn't guarantee it can just because they're good. Look at Gary Payton win LA: Hall of Famer who couldn't fit his role as jump-shooting 4th option. Same with Pippen on the Rockets at the end of his career.