The movie was filmed on an abandoned mining island.
The Colossal Titan is depicted in the manga and anime series as being 60 meters tall. In this film adaptation, the creature's size has been doubled to 120 meters.
Hajime Isayama was originally going to kill off most of the main characters as an ending, but changed his mind when the manga became popular.
The writer of the manga was going to have trees protect the city and not the wall but later decided that a big wall was better than a thick tree line.
Several character's personalities have been changed due to the writer's request, such as Eren becoming scared of the titans and is paralysed in fear when he first sees one instead of having the 'I must kill them all' attitude in the anime/manga. Mikasa's romantic interest in Eren is shown to a greater degree.