- Billing Displacement: Karen Black gets top billing even though she has the least screen time of the four leads.
- Cast the Runner-Up: Karen Black initially wanted the role of Blanche. She ended up playing Fran.
- Dawson Casting: In what has to be some kind of record for this, 78-year-old Julia Rainbird was played by Cathleen Nesbitt, who was in her late 80s at the time!
- The Other Marty: Alfred Hitchcock offered the role of Arthur Adamson to William Devane, but Devane had to turn it down due to other commitments, so filming began with Roy Thinnes as Adamson. Then about a week into the shoot, Devane told Hitchcock he was available. Hitchcock, who had doubts about Thinnes all along, fired him and refilmed his finished scenes with Devane (mainly the drugging/kidnapping of the priest at the cathedral. Some long shots of Thinnes from that sequence still made it into the final cut). Thinnes was with the film long enough to appear in a promo shoot with Hitchcock, Black, Dern and Harris.
- Playing Against Type: Bruce Dern as a hero (or, at least, someone who's trying to defeat the villains).
- Throw It In!:
- The actors were told that they could ad lib parts of their dialogue. Barbara Harris, an alum of The Second City, obviously would've been comfortable with this.
- The final shot in the movie, a wink by Harris, was a jokey reference that was not planned but Alfred Hitchcock decided to leave in.
- Troubled Production: Hitchcock began development for the film in 1973. After Frenzy screenwriter Anthony Shaffer turned down Hitch's offer to script the film, North by Northwest writer Ernest Lehman took over. But Hitchcock's health took a turn for the worse; he suffered a heart attack, had a pacemaker installed, then suffered some injuries from falls, which made it seem doubtful that it would ever get made. By 1975 he'd recovered enough to start filming, though his health was still a concern throughout. As mentioned in The Other Marty, filming had to restart when the role of Arthur Adamson was recast.
- What Could Have Been:
- Alfred Hitchcock originally wanted Jack Nicholson for George Lumley, but he was busy with One Flew Over the Cuckoo's Nest. Al Pacino was offered the role, but his asking price was too high. Robert De Niro and Paul Newman were also considered.
- Faye Dunaway was offered the role of Fran.
- Goldie Hawn was considered for Blanche. She went on to star in the very Hitchcock-like Foul Play two years later. Liza Minnelli was also mentioned for Blanche.
- Lillian Gish wanted to test for the role of Julia Rainbird but the role had been promised to Cathleen Nesbitt.
- Originally Alfred Hitchcock himself was supposed to walk down the stairs and wink at the audience instead of Barbara Harris. Ultimately he decided against it.
- Burt Reynolds was considered for the part of Arthur Adamson. Hitchcock watched The Longest Yard to see if he was right for the role. Hitchcock was instead impressed with Ed Lauter and cast him in the role of Maloney. Roy Scheider was also considered.
- Working Title: Began production as Alfred Hitchcock's 53rd Filmnote , then later got the more formal titles Missing Heir and Deceit, with Family Plot chosen midway through filming. Hitchcock also joked that he was considering the title Alfred Hitchcock's Wet Drawers.
Trivia / Family Plot