Trivia: Near the end of the film, Superman gives a press conference in front of a bluish mirror-glass building which is meant to be the Daily Planet skyscraper in Metropolis (which we all know is New York, sort of). The shot is framed so you can only see the bottom of the building - necessary as it is only about 3 floors high, and is in fact the railway station in Milton keynes, England, about 400 yards from where I work. Even the crowd have a vaguely British look about them - presumably passers-by were recruited and stood there in their own clothes (this would matter less now - Brits look more American than they did in the Eighties).
Trivia: Christopher Reeve said in his autobiography that he much preferred Richard Donner's approach rather than Sidney J. Furie's. He mentioned that if Donner had done the scene with Superman walking up to the big UN building, he would have shot on location of where that building in real life is, choreographed thousands of extras, had cars driving by on the street and cut to real shots of people gawking out of office windows. Instead, Furie shot at an industrial park in London with a giant matte painting, only a few extras, no buildings or cars and a couple of pigeons for added effect.