Harry Potter and the Deathly Hallows
With a hugely talented group of actors like in the Harry Potter, it’s only expected that some moments were made up on the spot. Within Harry Potter and the Deathly Hallows Part 2, there was one scene in particular that Ralph Fiennes played around with while portraying the evil Lord Voldemort. As he gave that last speech, he kept changing it every rehearsal, in order to elicit different but genuine responses from the cast every take.

Harry Potter And The Deathly Hallows
The Terminator
Back to James Cameron, with his movie, The Terminator. Just one small little thing that Cameron allowed to stay in the final cut, despite being unscripted, became inseparable from the film. Back when Arnold Schwarzenegger goes to the police station, the script only read that the cyborg should leave, disappointed. Well, it was the actor himself, Schwarzenegger, who added in, “I’ll be back.” Sure enough, Cameron love the line and ended up including what was intended to be just a minor character in the rest of the movie and sequels.

The Terminator