The original idea for the movie was to adapt a singular story (that concept became the 1988 sci-fi film Miracle Mile) before the show's success in syndication led to the decision to make it an anthology.
The scene with Vic Morrow's tragic accident was supposed to end up with his character pulling a Heel-Face Turn when he rescues two Vietnamese children.
Also, Steven Spielberg was to have adapted "The Monsters Are Due on Maple Street" before Morrow's death led him to change his mind and adapt "Kick the Can" instead (the former was to have required many effects shots and night shooting with children, similar to the segment with Morrow).
It was originally intended to have Spielberg's "Kick The Can" be the final segment, but following audience previews the order was changed. (Interestingly, Jerry Goldsmith's end credit music [which represents all but the Landis episode] unintentionally reflected the change, as he composed the music before that decision had been made.)