MAPPA brought back Arifumi Imai, the animator who single-handedly worked on the Levi vs Kenny and Levi vs Beast Titan scenes from season 3, for the finale.
The scene where the Wall Titans are marching near a cliff where the citizens are stranded and left to die contains an homage to Steven Spielberg's 1993 film Schindler's List. In that scene, the screen itself is in usual color, but is then shifted to black and white much like the film, but the only people who are in color are the mother and her baby, the latter of which is seen wearing red clothing. This seems eerily fitting, since the baby in red clothing is an homage to the little girl in red coat from the film, as a representation on the innocence of the Jewish youth who were killed during the Holocaust, much in the same manner as the baby in red clothing being a representation on the innocence of the youth outside the Walls of Paradis Island (which was Eldia's last standing territory) who were killed during the Rumbling.
The Special consists of chapters 135 - 139 of the manga.
In the manga, Armin and Eren's talk is not as long as it is in the anime. They added some new lines to the scene.
The crying baby during The Rumbling scene was voiced by Yuki Kaji's Baby.