I remember the part Turnbull explained, but I had forgotten that the time frame of her showing up at the mall was only 3 days after the detectives came to her house. The film affords the viewer no such clarification as to the timeframe of when Kay came to the mall.

Frank White's last post raised a question I had not considered until now: did the rest of the Corleone's ever know that Michael was married in Sicily? I would assume so through Don Tomassino. Maybe Mama never knew that Michael was married and her advice to Kay in the novel was because Mama truly believed Michael murdered McCluskey and Sollozzo.

Did the Barzini's and other Corleone enemies know that Michael was married or was the car bomb meant exclusively for Michael, with Apollonia being an accidental victim? Again, I would presume it was no secret to his enemies and that they could have found out when Fabrizzio turned traitor.