Continuity mistake: During Noah and Allie's first date, when Noah decides to lie down in the street, his head is lined up with the double yellow center line on the road. When Allie decides to try it, Noah has moved to nearly the middle of the right lane. (00:15:00)
Continuity mistake: When Allie tries her wedding dress on and the ladies are all squealing around her, she goes back and forth between having her earrings on and having no earrings on.
Continuity mistake: Allie has just walked into Noah's barn and is admiring his carpentry. The way her blue scarf is tied around her head changes from shot to shot. (01:16:50)
Continuity mistake: Older Noah goes to see the doctor who listens to his heart. On the wall are two x-ray films. The x-rays flip between shots, as evident by the position of the heart. At first it is on the left. When Noah gets up the heart is now on the right. (01:08:45)
Continuity mistake: At the very end, on the morning after Noah and Allie had died, the way the two hold each other's hands are different between shots. Note Noah's pinkie.
Continuity mistake: When Noah and Allie are passionately kissing in his car outside of her family home, she is wearing red nail polish. She has to leave, and runs up the steps to the door, where her father startles her. She is no longer wearing any nail polish.
Continuity mistake: Young Allie goes to meet Noah at his place the night they first visit the Windsor Plantation. The two kiss outside on the porch. The two move closer to the green shutter in the close-up shot.
Continuity mistake: On the 2nd morning Allie spends at the restored Windsor Plantation, she wakes up and finds Noah's note. The way the red blanket lies on her differs between shots. A corner is on the pillow in the close-up shot. (01:28:30)
Answer: She doesn't remember being married. Using her married name would only serve to confuse and upset her.