The young Otto is played by Truman Hanks, Tom's son, who was 26 years old during principal photography.
In the cars scene with Otto and Reuben, Tom Hanks' face was digitally de-aged to make him appear in his mid thirties. The VFX team used footage and stills from The 'Burbs (1989) to create a digital blueprint in order to achieve this effect.
The original Swedish film adaptation was nominated for two Academy Awards and was the highest grossing foreign film of 2016 in the United States.
Rita Wilson (Tom Hanks' wife) contributed to the movie soundtrack. She sang "Til You're Home" with Sebastian Yatra.
As Otto said to Marisol, the "Swedish éclair" pastry eaten in the cafe' is called semla. This is a nod to the Swedish origin of the novel on which the movie is based. The pastry, however, is not mentioned in the book. It is also not commonly found in Pittsburgh, roughly where the American movie takes place. Actually, in Sweden, semla is a seasonal food, generally only available between December and Easter, as it originates from christian tradition as a treat eaten before Lent.