Continuity mistake: When Lucy is in the Callaghan's house at Christmas at the very end of the scene it shows her stocking and her name on it is in white letters. However, in the scene where Mary comes in and tells the family that Lucy is pregnant, the camera pans to Jack who is standing right beside Lucy's stocking, only this time her name is in black letters.
Continuity mistake: When Lucy and Jack are walking along the river, a long shot shows them approaching a lamppost with a kissing couple. In the next shot, they pass the lamppost but there is no one there. They finally pass the couple at the next lamppost. (00:46:55)
Continuity mistake: When Lucy and Jack are moving the couch into Peter's apartment, Lucy gets bumped and falls into a table, knocking over a vase of flowers. (This table and vase are located directly below a mask on the wall.) Earlier in the film, when Lucy enters Peter's apartment for the first time (to feed the cat) we see her slowly entering the living room in the same area where she later falls - the mask is there, but the table and vase of flowers are not.
Continuity mistake: In one of the hospital scenes she has her purse across her chest, then the camera goes back and it's hanging from her shoulder.
Continuity mistake: When Sandra Bullock is sitting on her bed looking at Peter Gallagher's things, she dumps a can of cat food out of a paper bag. She turns it over, and you can see that there is no pull tab on either side. When she goes to his apartment to feed the cat, she pops the can open, but she would've needed a can opener for a can without a pull tab.
Continuity mistake: In the Christmas family picture scene, the camera seen in Elsie's hand is a Brownie camera(35mm size). When picture is actually taken, she uses a flat type(110 size film) camera with a tall flash on it.
Continuity mistake: In the scene where Jack comes home and sees Lucy asleep on the front couch, when he walks in the front door, there is a window in the door without a curtain. In the morning when Lucy goes to leave the house, the window has a curtain on it. When there isn't a curtain, you can still see the little metal things on the door where the curtain would hook in.
Continuity mistake: Sandra Bullocks' haircut keeps changing slightly throughout the whole film. Sometimes her fringe is very short and frizzy, other times it is long enough to tuck behind her ears.
Continuity mistake: Peter Callaghan is in the hospital with amnesia after his accident. His old girlfriend from Portugal, Ashley Bartlett Bacon, comes to visit him. Peter tells Ashley that he's getting married to 'Lucy'. Ashley asks 'Lucy who', and Peter states that he can't remember her last name. A little bit later in the scene, Ashley leaves, and Lucy comes to visit him. Peter says: 'My family loves you, I might as well love you. Lucy Eleanor Moderatz, will you marry me'. He addresses Lucy by her first, middle, and last name, after just having told Ashley moments earlier that he couldn't remember her last name.
Continuity mistake: When Mary and Beth are standing outside Lucy's booth, there is a man waiting behind them. When Lucy lets them through the turnstile, somehow he has moved inside the gate to the right of the turnstile without going through it, and a woman is in his original position. (00:56:00)
Continuity mistake: On New Year's Eve when Lucy leaves her apartment to go to her friend's party, she meets Jack. On the ground is a significant amount of snow. When she gets to her friend's house, there is no snow anywhere to be seen. When she leaves her friend's house with Jack and is walking down the street, the snow is back. (01:00:00 - 01:02:00)
Continuity mistake: After Lucy stops the wedding and tells Jack that she is in love with him, they show Jack smiling and looking down. Behind him over his left shoulder, a man with a mustache and beard has appeared. He is not at the chapel before when they show the wide picture of the chapel, and then he is never seen again. (01:33:00)