To internalize her character, Priyanka Bose went to Madhya Pradesh to meet Kamla Munshi, the mother her character was based on: "My questions were basic and just by meeting her, I could tell how hard her life has been. I got down on my knees and hugged her and thanked her for her courage." When meeting Munshi she was told that she was declared crazy by many villagers in the small town for years, as she never gave up hope that her son would return one day.
The 8-year-old Sunny Pawar was originally unable to attend the US premiere because he was denied a visa. Producers of the film made an appeal to Homeland Security, after which Pawar and his father were allowed to come to the US.
At the Australian box office, it had the biggest-ever opening weekend for an Australian independent film. Among all Australian films, it had the fifth-highest opening of all time.
Google helped the production and gave the crew access to their satellite imagery to use in the film, providing them with versions of Google Earth from the correct time period, and providing a lot of technical support in order to shoot scenes featuring Google in-camera, which saved the production a VFX budget.
Dev Patel had to develop a new physique to portray Saroo and attended several hours in the gym in order to inhabit his part. He also grew a beard and developed an Australian accent (with Tasmanian dialect), visited Saroo Brierley's orphanage in India and wrote a diary while he took the original train ride that Brierley accidentally took as a young child. In total, he spent eight months preparing for the role.