Alright, I concede, the chances of a Roman Insutrial Revolution were minimal at best, although I do believe that with sufficient investment, scientific genius, and a lot of luck, a smaller scale one would have been possible. However, I am certain that steam could have been used on a smaller scale, e.g. to power small irrigation systems, conveyor belts etc, had more notice been taken to Hero's invention.
Also, although that picture of the Roman with the assault rifle is awfully cool, why does he have a thin iron helmet, when he has modern firearms?