<Li> Bryce Gheisar as eight - year old Ethan Montgomery </Li> <Li> Juliet Rylance as Elizabeth Montgomery, Ethan's mother . </Li> <Li> Peggy Lipton as Hannah (adult) <Ul> <Li> Britt Robertson as young Hannah </Li> </Ul> </Li> <Ul> <Li> Britt Robertson as young Hannah </Li> </Ul>

Where is a dog's purpose being filmed