Charlotte Ray Rosenberg grew so much during the shoot that, in some scenes, Josh Hutcherson had to stand on "an apple box or little wooden pancake" (0:08:42 in DVD commentary) to keep their height differences consistent in the film.
Gabe and Rosemary's on-screen "first kiss" was actually the first kiss for actors Josh Hutcherson and Charlotte Ray Rosenberg in real life.
Charlotte Ray Rosenberg 's aunt saw a casting call for the role of Rosemary in a newspaper. She took her niece, who has never auditioned for anything before, to the audition.
In the scenes where Gabe and Rosemary are talking on the telephone, filmmakers decided not to use cordless phones because they wanted an old-fashioned feel to the movie. This is also why Gabe is shown in Jockey briefs in scenes of his bemoaning lost love rather than the boxer shorts Josh Hutcherson preferred (see 0:37:00).
The scene where Gabe gets in trouble for running off with Rosemary was a real event that happened to the director with his girlfriend when he was 16.