Centuries from now, when the world is covered with water and humanity is extinct and the end of A.I. Artificial Intelligence becomes a documentary, the future computers trying to understand our civilization from the pop culture we’ve left behind will scratch their robo-heads at Mr. & Mrs. Smith. Ancient records speak of the rise of some kind of symbiotic organism known as “Brangelina,” and then some years later its dissolution. The robots uncover an enormous amount of fascination in this creature. There are thousands of pictures of this two-headed being smiling, looking glamorous, in front of backdrops festooned with corporate logos. Separately, the individuals that comprised Brangelina made many movies, but they appeared together only twice: In 2015’s By the Sea and in 2005’s Mr. & Mrs. Smith. Then and now, the film is one of the stranger works made in Hollywood in the 21st Century.