What are examples of irony in The Hobbit?
The most prominent example would be verbal irony.
If we are talking about the movie and not the book, then we see in the end of the first movie Bilbo Baggins say, "I do believe the worst is behind us. " (dont quote me on this word for word, this is coming from memory). However the worst was yet to come. That would be verbal irony since he says one thing, but the audience knows that he is wrong and the total opposite happens.