The British Board of Film Classification is still receiving complaints about this movie four decades after its release, due to the board's decision to classify it U (suitable for all). The BBFC admitted in 2012 that it had "received complaints about the suitability of Watership Down at U almost every year since its classification".

Considered to be the most violent animated PG-rated movie ever made.

In the U.K., this movie opened at the Empire, Leicester Square cinema, on the October 19, 1978, and expanded to the rest of the U.K. the following year. It became the sixth highest grossing movie of 1979 at the British box-office.

Was originally directed by John Hubley, who died in 1977. He and his wife Faith's work can still be found in the movie, most notably in the "fable" scene.

Most of the locations in this movie either exist, or were based on real places in Hampshire, England, and surrounding areas.

Sir John Hurt and Richard Briers (who played Hazel and Fiver, respectively, in this movie) returned to voice General Woundwort and the new character, Captain Broom, respectively in Watership Down (1999), a television series adaptation of the book. Frank Welker did return in the TV series from the film providing the animal vocals.

The first animated movie to be presented in Dolby Stereo in theaters.

In December 2011, property developers announced that they were planning to develop Sandleford Park, near Newbury, Berkshire, in a real-life parallel to the fictitious development of this area which prompted the rabbits to leave the warren in the book and movie of Watership Down. Richard Adams, the author of the book, plans to organize stiff opposition to the development. "I'm going to oppose it tooth and nail. It's a beautiful piece of open country and the most beautiful area south of Newbury. The very idea of building on it makes your gorge rise."

This movie was popular with adults, who attended late-night screenings.

The backgrounds and locations, especially Efrafa and the nearby railway, are nearly perfect matches to the diagrams and maps in Richard Adams' book.

His voicing of Kehaar was the last movie work for Zero Mostel.

This was the first movie to feature Sir John Hurt and Sir Nigel Hawthorne. Both appeared in two other animated movies, The Plague Dogs (1983), which was also based on a Richard Adams book, and The Black Cauldron (1985).

Watership Down is a real place, located in the south of Newbury.

Watership Down was adapted into a stage play in 2016. The show was performed at Watermill theatre and only had nine actors. It lasted from June 2016 to July 2016. It featured puppetry, physical theatre, as well as live actors.

Martin Rosen's directorial debut.

Alongside The Plague Dogs (1983), The Secret of Nimh (1982), and The Last Unicorn (1982), this is easily considered one of the darkest and most violent animated movies of the late twentieth century despite being rated PG in the cases of this movie and The Plague Dogs (1983), and G in the cases of The Secret of Nimh (1982) and The Last Unicorn (1982). All four of these movies were released before the PG-13 rating existed.

This film is part of the Criterion Collection, spine #748.

The first animated film to use dust.

The second animated movie to not be a musical after The Rescuers (1977).

The first theatrically released animated film to star John Hurt. Later he'd go on to voice Aragorn in The Lord of the Rings (1978), Snitter the Jack Russel Terrier in The Plague Dogs (1982), the Horned King in The Black Cauldron (1985), Mr. Mole in Thumbelina (1994), the Narrator in The Tigger Movie (2000), and Felix the Gull in Valiant (2005).

The first theatrically released animated film to star Nigel Hawthorne, later he'd go onto voice Dr. Boycott in The Plague Dogs (1982), Fflewddur Fflam in The Black Cauldron (1985), Brigadier G in Freddie as F.R.O.7. (1992), and Professor Archimedes Q. Porter in Tarzan (1999).

The first animated film focused on British accents to feature the voice of Frank Welker providing the animal vocals.