In the George Roy Hill classic, the real names of Butch and Sundance are Parker and Longbaugh, a fact that Christopher McQuarrie must have known while writing this film (and likely used to foreshadow the final shootout). So why doesn't IMDb have it listed under movie connections?
http://cinemablend.com
Also, the brothel in this movie is the same place they filmed the end of Butch Cassidy and the Sundance Kid.
Men build things. And then we die.
This is because the "Movie Connections" section of IMDb is used entirely by IMDB users rather than professional movie critics and stuff (or even IMDB movie critics) and the users may either have forgotten to add "Butch Cassidy..." in movie connections, or haven't recognized it because they haven't seen that movie or were just not bothered taking the time and effort to add it.
But you're right, it should be added!