{in no particular order}
~A scene in which Arthur Clennam actually does attempt to eat a toast crust bestowed by Mr. F's Aunt was actually filmed for Little Dorrit (2008) but was cut before release because the miniseries was running overtime already.
~Emma Thompson actually wrote the screenplay for Pride and Prejudice (1995) but sold it to Andrew Davies because she didn't want to be associated with two Jane Austen pictures in one year (what was she THINKING????).
~Anthony Andrews initially refused the role of Sir Percy in The Scarlet Pimpernel (1982) because he felt the character was too stupid, but after reading the book he saw the light and took the part.
~Sue Birtwhistle and Susie Conklin originally wanted Miss Matty Jenkyns to die at the end of Cranford (2007), but felt that fans might rebel as there were already so many deaths in the piece.
~Emma Pierson (Fanny Dorrit) and Sebastian Armesto (Edmund Sparkler) are actually married in real life.
~The infamous lake scene in Pride and Prejudice (1995) was written into the script (after Andrew Davies got ahold of it) when Colin Firth complained that he did not like having to wear a heavy coat and waistcoat in every single scene and wanted at least a short bit in which he wouldn't have to swelter.
~Jane Seymour hates wigs and refused to wear one in The Scarlet Pimpernel (1982), so she grew her hair out and then had it styled in a four-hour process every morning before filming.
~Richard Armitage signed on to play Mr. Thornton in North and South (2004) because he thought the movie was about the American Civil War-- by the time he realized he was to be a mill owner and not a Confederate general, it was too late to back out.
~Justin Bieber auditioned for the part of Marius Pontmercy in Les Miserables (2012) but was rejected because the casting directors felt he was not tall enough. The part eventually went to Eddie Redmayne.
~A scene was filmed in Emma (2009) in which Emma gave Harriet a complete makeover in hopes of attracting Mr. Elton, but the scene was eventually cut because it was felt to be too modern.
~The blue plaid crossover-bodice dress that Emma Thompson wears as Elinor Dashwood in Sense and Sensibility (1995) is an 1810 original believed to have been worn by Jane Austen herself.
~After much hassle involved with the revolutionary technique of live singing on set, Tom Hooper gave up trying to get Russell Crowe to sing along with the music and hired Josh Groban to dub his vocals for the big numbers. Crowe sings the minor dialogue bits, but it is Groban's voice that can be heard in The Confrontation, Stars and Javert's Suicide.
~The scene in which Anne Shirley dyes her hair and has it cut off was not originally in the screenplay for Anne of Green Gables (1985), though it does appear in the original novel. Megan Follows' hair caught on fire during a candlelit scene and had to be cut off as a result (though the actress was unharmed). A scene in which Anne's hair is cut off was hastily written into the script, and production was then halted for two years afterward while Follows' hair grew back so they could shoot the rest of the movie.
I have lots more, but I don't want to turn this post into a novel, so we'll stop there for today. Sources for all these bits of fun can be found here.
{inspiration for this post was inspired by the loverly Rachel}
