Woody Allen decided to make the film for two main reasons. One was because he had always wanted to do a "chamber piece", a film with a small cast (there are only six principal characters, and only nine in the entire film) in a single location. The other was for the location itself, Mia Farrow's Connecticut country house, which inspired Woody Allen to write the screenplay with the intention that it would be shot at the house. Unfortunately, by the time Allen finished the screenplay, it was winter and the location was unusable for a movie so firmly planted in September. The entire movie (which takes place in Vermont) was shot on a single soundstage at the Kaufman Astoria Studios in New York.
According to Mia Farrow's autobiography "What Falls Away", Woody Allen filmed two or three versions of every scene, took all of the footage into the editing suite, cut the film together and then decided that he hated it. He then rewrote the entire script, fired and recast virtually every major part, and re-filmed the entire thing. This meant that he doubled his production costs and came in well behind schedule. Allen was reportedly keen to do it all again for a third time.
Allen's intention was that the production should feel like a play captured on film. For that reason, he generally shot in long, uninterrupted takes with very few close-ups.
In the re-shot version, Maureen O'Sullivan, Charles Durning and Sam Shepard were replaced by Elaine Stritch, Denholm Elliott and Sam Waterston respectively.
In addition to these replacements, there was one more that did not even make it through an entire shooting. At the very beginning of shooting, Christopher Walken played the role of Peter but Allen only shot a few scenes with him before he decided that he was wrong for the part. Walken was replaced by Sam Shepard who, in turn, was later replaced by Sam Waterston.
In Elaine Stritch's one-woman Broadway show, "At Liberty", she reveals that after the wrap party she had an attack of hypoglycemia at the door of her hotel room, and was rescued by the mini-bar attendant who gave her a Pepsi. This event caused her to completely give up alcohol.