One of the reasons the MCU movies are so well-loved is definitely because of the witty dialogue. They've had some great lines that lived on in the memories of Marvel fans. The release of Avengers: Endgame brought an end to the current phase of the MCU, and to the sadness of fans, it brought the end of Robert Downey Jr. playing Tony Stark/Iron Man. But Tony Stark went out memorably, with one final line. And while viewers loved Ton's last line, it almost didn't make it into the movie.