Anthony Hopkins deliberately provoked Jodie Foster off-camera by mocking her rendition of a West Virginia accent, which helped her convey Clarice's outrage when Hannibal taunted her for hiding her in-character accent.
When filming phonecalls, it is standard practice to film both sides separately and have the actors pretend they're having a phone call. At the end of Silence they hooked up the phone to the phone network and had Hopkins call from the set of another movie across the country. When Jodie Foster picks up the phone and Hopkins speaks back to her the look of surprise on her face is genuine.
Life Imitates Art: In the book, the FBI approaches Johns Hopkins, a known center for sex-reassignment surgery, for help tracking down Buffalo Bill. The institute refuses, objecting that this would give transgender people a bad name. After this exchange was cut from the movie, real-life activist groups made the same complaint about the film. In the book, the FBI was able to get what they needed by emphasizing that they didn't want names of people they'd approved for the surgery, but of people they'd rejected because they were not transgender. The diagnosis of Lecter's that they were going by pegged Buffalo Bill as more of a transsexual wannabe.
Throw It In: Ft-ft-ft-ft-ft-ft. Hopkins threw this in as a joke at the end of the take (hence the long pause between the end of the line and when he actually starts the noises) but the director decided it was appropriately creepy and kept it.
Louis Gossett Jr. auditioned for the part of Hannibal in Silence but claims he was turned down partly because they didn't want to make him a Scary Black Man.
Silence was initially put together at the behest of Gene Hackman, who planned to direct and star as Hannibal Lecter. Hackman left the project after his daughter urged him not to make it.
Jonathan Demme's original choice for Lecter was Sean Connery, who turned it down because he considered it disgusting. Robert Duvall was considered for the role. Dustin Hoffman, Robert De Niro, John Hurt, Christopher Lloyd, Patrick Stewart, Jack Nicholson, and Jeremy Irons are also rumored to have been in the running. Michelle Pfeiffer was Demme's original choice for Starling, and her refusal cleared the way for Jodie Foster. Mickey Rourke was offered the part of Jack Crawford and turned it down.
Other actresses considered for the role of Starling included Nicole Kidman, Halle Berry, Andie Mac Dowell, Meg Ryan, and Melanie Griffith
In addition to Rourke, Michael Keaton and Kenneth Branagh were all considered for the role of Jack Crawford.
You Keep Using That Word: On a meta sense. Zehava Gal’on, leader of the Israeli leftist party Meretz, has often criticised right-wing and religious leadership in Israel for their conspicuous silence on growing nationalist chauvinism and intolerance and the violence these attitudes beget, labelling their behaviour as ‘the silence of the lambs’. This is despite the fact that the name derives from Clarice’s personal history living in a farm where sheep were slaughtered: the sheep would let out blood-curdling screams, and when Clarice couldn’t tolerate it any longer she tried, in vain, to grab a sheep and run off to save it; this even inspired her to join the FBI, to overcome her inability to protect the weak and make the metaphorical lambs stop screaming—in other words, ‘the silence of the lambs’ is a good thing.