Disney asked that the budget be cut by approximately $20 million, and when the film was released on Christmas Day, it flopped at the box office. Robin Williams blamed Disney's marketing and the loss of content the film suffered because of the budget cuts. As a result, he fell out with Disney again.
The aria that Andrew is listening to when he first uses the record player is from Dvorak's opera "Rusalka." The opera is concerned with the fairy-tale story of a water nymph who wants to become mortal for love.
The final scene in which the nurse robot stops life support systems on request is invalid; the First Law of Robotics would have prevented it. No amount of begging would result in a positronic robot assisting in suicide or euthanasia. In fact, according to Asimov's stories, even witnessing a human being hurt might destroy a robot's positronic brain and the movie acknowledges the Three Laws of Robotics.
When Andrew is walking through the park with Portia, his shirt is wide open. When they stop to talk, it is almost closed. When they walk again, it is open again.
During the conversation between Andrew and 'Sir' after Andrew jumped out the window, a clump of grass caught in Andrew's neck joint appears and disappears.