Dawson Casting: 26-year-old South Carolinian Edward Rutledge, the youngest man in the Congress — "except for Ben Franklin" — was played by then-42-year-old John Cullum.
True of the original Rutledge, Clifford David, as well: he was 37 when the show opened.
Averted with Ken Howard who was only 28 when he portrayed Jefferson in the movie, and 25 when he was in the show on Broadway.
Executive Meddling: Literally! Then-US President Richard Nixon convinced friend and producer Jack Warner to expunge the musical number "Cool Considerate Men," an ode to wealthy conservatism sung by the antagonist, from The Movie for purely political reasons — and not just remove it but destroy all the footage. As Warner was no longer working with his and his brother's namesake studio, however, the employees responsible merely packed it into unmarked boxes and stashed it with all of the other film negatives, letting Paramount Pictures rediscover it for the Special Edition. Nixon had earlier attempted to pressure playwright Sherman Edwards into removing the number after seeing a performance of the play at the White House, but Edwards refused. Guess that makes this ExecutiveBranchMeddling. Or Chief Executive Editing.
Irony as She Is Cast: In the original cast, one of the best singing voices belonged to Edmund Lyndeck, the original Witherspoon. Witherspoon doesn't sing a note.
The Pete Best: Paul Hecht and Clifford David originated the roles of John Dickinson and Edward Rutledge, respectively, but it was Donald Madden and John Cullum who created the most enduring versions of the characters in the film version.
Very narrowly averted by Howard da Silva, the original Franklin, who had been regarded as a bit of a prima donna that the director and writer didn't want to deal with, especially since his understudy, Rex Everhart, did as good a job as him (Everhart performed with the cast for four months while da Silva was hospitalized). According to the director, when it came time for the film, Da Silva promised that if he got the part, he'd behave like a little angel. It worked, and Da Silva behaved himself.
Playing Against Type: Both William Daniels and Howard da Silva were cast wildly against type. Circa 1969, Daniels specialized in meek, ineffectual, and prematurely middle-aged characters, while da Silva was best known as a nasty villain (like Jud in the original Oklahoma!). In Daniels' case, characters like Dr. Craig and Mr. Feeny were a result of post-1776 typecasting.
Gregg Edelman's casting as Rutledge in the 1997 Broadway revival was considered startling at the time, as Edelman was then best known for playing good-natured romantic leads.