When Abbey and Kevin kiss at the end of the movie, Abbey is wearing a blue-jean jacket. When the picture of this scene appears in the newspaper, she's wearing a black leather jacket.
When we meet Brady Francis he is shown playing a Game Boy, complete with sound effects. There is no game cart in the Game Boy.
When Kevin is waiting to meet his "L Train Girl" at their place, the clock shows that it is a few minutes past 7 o'clock. When she finally shows up and they embrace for a kiss, the same clock now shows that it is 6:50.
When Kevin meets Abby and she begins to fold a paper airplane, she folds the paper in half horizontally. The plane she's holding in the immediate next scene could not have been created with horizontal fold to start its creation.
The crowd awaits to see if Abbey will appear at 7:00 pm in the train station. Everyone is dressed for cold weather. Yet at 7:00 pm, the sky should be dark.
In the scenes involving softball, a 12 inch ball and mitts are used. Chicagoans play 16 inch softball without mitts.
The "Are You Her?" posters don't include a phone number even though on the poster it is written "My phone number is.." and Kevin is contacted through the phone by the "L-train Girl."
Throughout the movie, all of the characters mouths do not match the audio. It's apparent that all of the cuss words were taken out during voice dubbing in final production. For example, when Brady Francis finds out that Kevin's friends are taking the girls out, his voice says "his butt is mine" but his mouth clearly says "his ass is mine."