R.J. Palacio was inspired to write the book after taking her son out for ice cream, where they saw a child with Treacher Collins Syndrome. Her son cried at the sight of this boy. This story is used in a scene from the film, where Jack Will's (Noah Jupe) mother is reminding him why it's essential to make Auggie feel welcome.
Auggie's facial deformity is called Mandibulofacial Dysostosis (MFD), also known as Treacher Collins Syndrome.
Jacob Tremblay and his family went to the Children's Craniofacial Association retreat, where he got to meet and befriend children with Treacher Collins syndrome, the same syndrome that Auggie has.
Jacob Tremblay's prosthetic make-up, designed and created by Arjen Tuiten, took an hour and a half to apply. It consisted of a skull cap with prosthetic ears attached, a facial prosthetic covering Jacob's face, and a wig to tie it all together.
The bicycle that August (Jacob Tremblay) is riding in the film is the same bicycle that Elliott is seen riding in E.T. the Extra-Terrestrial (1982).
R.J. Palacio: During the graduation scene, as one of the audience members; she can be seen sitting next to Jack Will's mother (Nicole Oliver) behind the Pullmans.