- Box Office Bomb: Willard only made over $6 million (with an additional worldwide gross of over $1 million) against a $20 million budget.
- Breakaway Pop Hit: Michael Jackson's performance of "Ben" (which was written for the original movie's 1973 sequel) is probably more popular than either the book or the two movies.
- Completely Different Title: The film's Spanish title is La Revolución de las ratas, meaning "The Revolution of the Rats".
- Keep Circulating the Tapes: The book is out of print (though it can be found on amazon, the copies are often in horrible condition) and the 1971 movie is only on VHS.
- The book was finally reprinted by Valacount Books in 2013.
- Shout! Factory is FINALLY releasing the film on Blu-ray/DVD in 2017.
- Money, Dear Boy: According to Ernest Borgnine's autobiography, they offered him a choice of a higher salary or a percentage of the box office. Borgnine chose a higher salary.
- Romance on the Set: Bruce Davison and Sondra Locke were dating in real life at the time the movie was made in 1970. They were never together publicly as a couple because Locke was married.
- Too Soon: Arguably an inversion. Robert Bloch wrote Psycho when the Ed Gein case was still fresh in the public's mind. For whatever reason, Gilbert waited 8 years. Each book was adapted to film, and each film had a remake, but Bloch's yarn is definitely more well-known. If there was ever a case against tactfulness, this would be it.
- Underage Casting:
- What Could Have Been: In the 2003 remake; there's an alternate ending which is true to the source material. In the alternate ending, Willard is instead overwhelmed and consumed by the mischief of rats while Ben looks on.
Trivia / Ratman's Notebooks