- Cast the Expert: The cab driver who takes Harry to the bus station, Muriel Beerman, was an actual New York cabbie that Paul Mazursky had gotten a ride from during the film's pre-production.
- Dawson Casting: Melanie Mayron was 21 when she played 16-year-old Ginger.
- Real-Life Relative: That's Mazursky's daughter Jill as the girl building the sandcastle in the last scene. She went on to be a screenwriter, collaborating with J. J. Abrams on some of his early work (like Gone Fishin'), and later a documentary producer.
- Unintentional Period Piece: Very much one for America in the early part of The '70s, back when hitchhiking was still common and you'd pick up hikers on their way to join hippie communes.
- What Could Have Been: Mazursky offered the role of Harry to Danny Kaye, who was interested but wanted the script to have "more jokes". Mazursky didn't want to upset the comedy/drama balance in the script, so Kaye ultimately said no. James Cagney, Cary Grant and Laurence Olivier were also considered.
Trivia / Harry and Tonto