Will Smith didn't believe it was really Steven Spielberg on the other end of the line when the executive producer first called to talk to him about Men in Black (Hombres de negro) (1997).
Tommy Lee Jones only accepted the role of Kay after Steven Spielberg promised the script would improve. He had been disappointed with the first draft, which he felt did not capture the tone of the comic.
The site BadAstronomy, famed for bashing science fiction movies (such as Armageddon (1998)) about their science blunders, praised this movie for being comedic, yet surprisingly accurate, when it comes to astronomy facts.
Will Smith, after reading the script, did not want to accept the role because one year before he had starred in Independence Day (1996) and he didn't want to make another movie about aliens. His wife Jada Pinkett Smith convinced him to take the part.
John Landis was offered the chance to direct, but declined, feeling it was basically just "Granujas a todo ritmo (The Blues Brothers) (1980) with aliens". He has since said that he was wrong, and he regrets turning down the film.