Corrected entry: At the hospital, Michael must defend his father, so he and Enzo the baker stand on the steps to the entrance of the hospital. The Turk's hit men drive up, see them, and drive away. Very soon, McCloskey and a large group of cops drive up, sirens blaring. They obviously have been informed by the hit men of the Godfather's new protection, and are there to rectify the situation. The problem is, that from the moment the hit men leave and the police sirens are first heard, only 22 seconds have passed. There is no way in this cell phoneless era that the hit men could have found McCloskey, informed him of the changed situation, and then have this police task force assemble and drive to the hospital.
Corrected entry: The age of Tom Hagen when he moved in with the Corleones is never consistent. At the start of Book I, Michael says Tom was 12 when Sonny brought him home and demanded they take him in; later in Book I, Tom says both he and Sonny were both 11. Then, in Book III, when recounting how Sonny had taken part in an armed robbery when he was 16, Don Corleone says that Tom had been living with them for three years at this point, which would place Sonny and Tom at 13 when Tom moved in.
Correction: It's not really a mistake. For one thing you're being too precise about the timeline. People's recollections of exactly when something happened or how old a person was many years before, is often vague or generalized. (I often don't remember how old I was when certain things happened in my childhood.) Michael, being the youngest Corleone child would have been around five or six-years-old when Tom Hagen moved in and may simply remember it incorrectly. Also, Tom could have been just weeks shy of his 12th birthday, technically making him 12-years-old and just a little over one year after that he'd be turning thirteen. Also, the Don was getting older at this point and his memory was not as sharp as it used to be and he may have remembered Tom as being around 13 when he moved in.
Correction: The police were likely right behind them to protect them in case something happened. When they saw that the car didn't stop and have its occupants exit, they drove up.
Greg Dwyer