10 Things You Didn’t Know About Indiana Jones And The Last Crusade
7. The Sewers Featured 2,000 Rats
Obviously, they didn't use a real sewer for the crypts underneath Venice - it was built inside England's Elstree Studios, as was a lot of the Venice section of the film like the library, portions of the boat chase and the second half of the prologue.
For the sewer/catacomb scenes, the script called for a large number of rats to not only terrify Alison Doody's Elsa, but eventually be set on fire when the guardians of the Holy Grail attempt to stop our heroes discovering its location. Wild rats carry a lot of diseases however, so for the film, over 2,000 rats were bred specifically for these scenes.
A horror for a lot of musophobics, but Alison Doody and Harrison Ford enjoyed these scenes as they were clean and well looked after. Ford also had a pet rat when he was younger, so knew how to hold and treat them.
Of course even back in 1989 you couldn't set real rats on fire. So for the firey escape, Spielberg used a combination of clever camera work, special effects and remote controlled rodents.