Especially noticeable as Brad is played by Young Neil's actor from the same film.
Creator Backlash: Minor example. Emma Watson says she refuses to watch her kissing scenes or the Rocky Horror scene.
Dawson Casting: Averted with Ezra Miller as Patrick, who was 18, but played straight with 21-year-old Emma Watson as a high school senior. Logan Lerman was eighteen, two years older than his character. Also Lerman is nine months older than Miller, who plays a character nearly four years his senior.
Freeze-Frame Bonus: Patrick's report card actually says "Patrick Nothing". Also if you look at Charlie's birthday cake, there are sixteen candles on it - which indicates that he's sixteen years old. And you can read the name 'Samantha Dutton' on Sam's SAT results, telling us what her full name is.
John Hughes originally had the film rights and planned to make the movie more as a dark comedy. Shia Le Beouf would have played Charlie, Kirsten Dunst as Sam and Patrick Fugit as Patrick. However his sudden death meant that the project was shelved, and eventually made as an independent film with the original author directing.
A subplot involving Candace telling Charlie she is pregnant and going to get an abortion was filmed, but cut from the film to avoid an R rating.
Alice being a lesbian was cut from the original book.