Revealing mistake: When Troy crouches down on the rocks, and leans down to see his reflection in the water, oddly the reflection is not reversed, yet his hair is combed the opposite way. (Did the director actually think that if Troy's hair was combed the opposite way it would pass as a reversed reflection?) Additionally, when he crouches down, the bottom button on Troy's shirt is unbuttoned, but in the reflection (as well as in the previous and following shots) the bottom button is buttoned up.
Revealing mistake: Although set in the 1960's, the school bus lettering was Arial, a font not invented until 1983.
Revealing mistake: Right after "Without Love", we see Edna answering the phone. If you've seen the movie as many times as I have, you'll see that this is a recycled shot from earlier when Mr. Pinky calls.
Revealing mistake: The first morning, when Robert takes Giselle to work, they enter atrium of the Time Warner Center (the well-known statue of the female Giselle admires is one of a set, the other is male), which is located at 8th Ave and Broadway, at the southwest corner of Central Park. Upstairs, when Sam tells Robert that she can't find where Giselle is from, and then when Giselle speaks to Phoebe, the very distinctive Johnson Lipstick Building (it's reddish and has three receding oval-shaped levels) at 53rd and 3rd is seen outside the window. The office scene is obviously not filmed at Time Warner, because it's impossible to be in an office at 8th and Broadway, on the West Side, and be next door to a building located at 53rd and 3rd, on the East Side. (00:35:40 - 00:40:35)