Saroo's Situation (Dramatic Irony)
While the viewer is powerless to help the young lost Saroo and do not know any more than he does, there is a dramatic irony in the fact that we have seen his journey to homelessness in Calcutta, and know that he has a loving family at home. In this sense, there is a disconnect between what the viewer knows and what the other characters—who see Saroo as simply a desperate orphan without a family—know about him.
Guddu Taking Saroo with Him (Dramatic Irony)
Saroo gets lost in the first place after begging his brother Guddu to take him along on his journey without their mother's permission. While we know that the brothers are orchestrating this journey, their mother has no idea.
Noor's Betrayal (Situational Irony)
In Calcutta, Saroo meets Noor, who seems like a kind person and offers to look after Saroo. However, we soon see that she has more nefarious and avaricious intentions, which luckily, Saroo intuits, escaping in the nick of time. This ironically shows Saroo that not everyone who is kind can be trusted.
Guddu's Death (Situational Irony)
At the end of the film we learn that Guddu, Saroo's brother, was killed on the very night that Saroo ended up on a train to Calcutta. Thus we see the irony of the fact that Saroo was separated from his brother not because of neglect, but because of a fatal accident that took place not far away from where Saroo fell asleep on the bench.
