However, a veteran who has shifted his interest in romantic movies to films adapted from real-life stories in recent years, Chan recalls that one of his top challenges was casting.

"As most of the boy's scenes feature him lying on a stretcher or a hospital bed, we need a child whose eyes are comparatively big, more easily to express emotions such as enduring the pain and missing his mother," explains the director.

Parman Parhat, a six-year-old boy from Emin county in northwestern Xinjiang, was selected to play the boy. Never having acted in a movie before, he received acting lessons for two months before shooting started in September last year.

In order to help the child quickly adapt to his "job", the director figured out a set with special guidelines: to start shooting mostly in the evenings, hence his tired state would match the role; and shoot the scenes within its natural timespan.