Wait, That Wasn’t in the Script!?

The best joke in Parks and Recreation, ad libbed by Chris Pratt

Indiana Jones and the Last Crusade, when Indy asks his dad how he knew Elsa was secretly a Nazi. Like father like son, I suppose.

The 2005 Royal Rumble, a 30-man Battle Royale where you have to be thrown over the top rope to be eliminated. It came down to Batista and John Cena, with Batista booked to win… and then he botched the last move of the match, sending him over the top with Cena. Then they had to improvise a new ending on the fly