There is a point where only one Anna is running down a hallway and hiding. While running down the hallway, her hair is left long and free-flowing. When she's gets in and out of her hiding place, however, her hair is done up in an elaborately braided hairdo.
The year of Anna Zimmerman's death is indicated as 1957 in the picture Michaela is holding in the beginning of the story; later at the Princeton Library, Anna Hart reads that the death happened in 1958.
While telling Anna H about the ride to school with Michaela, Rowan makes a bowl of cereal from the liquor bar in the living room where Anna H is watching TV. It seems the screenwriter needed something for Rowan to do while Anna H listened to the TV report and eating a bowl of cereal should work. Realizing the family keeps bowls, spoons, milk and cereal at the liquor bar in the living room, doesn't work.
The door to room 117, where Anna H is kept at Albacore island has a lockable knob and handle. Two of the other doors Anna H checks housing other Anna's only have the handle, no lockable knob. In a close up, when Anna H is speaking to Anna S through the door, there is clearing no lockable knob. Either Anna could have opened the door.
Rowan tells Anna the ride to school leaves in 3 minutes, then proceeds to make and eat a bowl of cereal.
Anna H jumps on the gurney to hide from Nurse Grap. The Nurse pushing the gurney doesn't recognize the extra 75lbs of weight from Anna H as she continues down the corridor.
Graham chooses to stay at the "Y" when he moves out of the family home. They have means, Graham is still employed, a hotel would make a more appropriate location for him.
Sarah tells Rowan and Anna H that they typically wait until puberty to tell the Anna's the truth and has a disposition that Anna H is years away from hearing that truth. Anna H is 12yrs old, she cannot be far enough from puberty for that to be an issue.
Anna H tells her guidance counselor that her grades are slipping due to a 'boyfriend that is giving me trouble'. The guidance counselor accepts that response from a 12yr old girl with no follow up to the parents.
Anna H and Rowan sleep late the morning of her escape from Albacore Island and ruin their escape plans. Anna thinks she is going to be killed that morning, doesn't seem likely she would oversleep. Rowan broke into the facility for the sole purpose of breaking Anna H out, seems unlikely he would oversleep.