Spielberg went through with Kubrick's idea for the ending knowing full well he would be Misblamed for it, since it was sappier than Kubrick's usual fare. All because Kubrick was his friend and Spielberg wanted to keep his vision alive.
Technology Marches On: Dr. Know is basically a public database with a fancy interface that can answer any question you have. In effect, it's just a less convenient version of Google that you have to pay to use.
Gigolo Joe was originally conceived by Kubrick as a GI Mecha, but screenwriter Thomas Watson suggested changing him to a male prostitute.
Chris Cunningham was originally the special effects supervisor when the project was being developed in the early '90s. None of his work ended up in the final film.
Part of the reason Kubrick's vision of the film languished in Development Hell for so long was was because he wanted the main character to be played by an actual robot. As of this writing, such robots are still impossible.