Paul Greengrass said in an interview in the New York Times on 12/30/2020 how this movie "is the first film I made with a child actor at the heart of it", and he thought that it would be very difficult to cast the role of Johanna, but when he saw Helena Zengel's audition, he said she "was the only person I really had to look at" and that it "was the easiest decision in the film".
Even after landing the role of Johanna in this film, German actress Helena Zengel still didn't know who Tom Hanks was until after the actual film shoot began and she was in the makeup trailer when Tom walked in and introduced himself. Thereafter the pair got on incredibly well and became such good friends over the course of the production, they continued to correspond after the film wrapped.
Twelve-year-old German actress Helena Zengel first came to the attention of director Paul Greengrass after he had seen her dynamic performance in the acclaimed German film Systemsprenger (2019) at the 2019 Berlin Film Festival. Greengrass was particularly impressed by how expressive her eyes were, as this is just what he needed for the role of Johanna who would have minimal dialogue in many of her scenes. Helena went on to attend casting calls in her hometown Berlin, and then in London where she formally met with the producer and director.
Pre-production lasted six weeks in New Mexico, including three weeks training in Kiowa language and customs for newcomer Helena Zengel. One skill Helena did not have to master, however, was horseback riding, as she'd been doing that since age four.
Tom Hanks: [captain] This is the sixth time Hanks has played a character with the title or de facto position of Captain. News of the World (Capt. Jefferson Kyle Kidd), Greyhound: en la mira del enemigo (2020) (Cdr. George Krause, who, though holding the rank of Commander, was the captain of a vessel), Sully: Hazaña en el Hudson (2016) (Capt. Chesley Sullenberger), Capitán Phillips (2013) (Capt. Richard Phillips), Apolo 13 (1995) (Capt. Jim Lovell), Rescatando al soldado Ryan (1998) (Capt. John Miller).