FILM 1382: THE DESCENT
TRIVIA: No real caves appear anywhere in film, they were all sets built at Pinewood Studios, London created by Production Designer Simon Bowles.
The appearance of the creatures was kept secret from the cast members until the first scene in which they encounter them was filmed. When the cast were finally filming the scene where the girls encounter the crawlers, the girls were genuinely scared and screamed the building down, running off set and laughing.
There is a shot of a "Crawler" much sooner than you think. Not long after they start the descent, in the cave that they light up red, when Sarah hears children's laughter as is checking out where it's coming from, look in the background to her left and you'll see a silhouette.
As stated in cast commentary on the Special Edition DVD, Shauna Macdonald, Natalie Mendoza and Alex Reid did the entire white water rafting sequence on their own without any stunt doubles or special effects.
The jokey production name given during filming was "Chicks with Picks".
This film's poster art is borrowed from a portrait photograph by Philippe Halsman of Salvador Dalí, entitled Salvador Dali In Voluptate Mors. (The photo itself was inspired by surrealist Dali's gouache Female Bodies as a Skull painting) This same imagery was also used for the poster for The Silence of the Lambs (1991).
Except for Sarah's husband, and some non speaking extras in the hospital scene, no men appear the film.
The park where the women are supposedly meeting, "Chatooga National Park" does not exist. The name references the Chatooga River which is the river from the movie Deliverance, which is loosely referenced in this movie (rough nature versus city dwellers). In Deliverance, this is the river that leads Lewis and friends into trouble.