I really wish I could see the stage notes Josh Hartnett was following, because I can only assume they said "I know we just said he was a convincing liar, but play it like a man who's never told a lie in his life...and Ham it up."
Honestly, this was fine. It's pretty fun, schlocky, nonsense, and mostly a vehicle for Shamalan's daughter's music career (clearly not acting). And that is fine.