Albert Finney felt the lead role wasn't serious enough, and agreed to star only if he got a producing credit; he later traded the credit for profit participation.
Hugh Griffith was reportedly drunk through much of the production; the scene in which his horse falls on him was not planned, and many believed he was saved by virtue of his inebriated condition. The film incorporated every frame of footage before rescuers entered the frame to save him.
Much of the scene in which Tom Jones and Mrs. Waters are eating together was improvised during the three hours it took to shoot, and the actors felt the effects from the food for days.
First credited film role for Lynn Redgrave. (Redgrave had one previous film role, a "blink and you'll miss it" uncredited bit part in Shoot to Kill, filmed three years before this film.)
The production of Tom Jones was a bit of a family affair. At time of production, director Tony Richardson was the son-in-law of Rachel Kempson, who portrayed Bridget Allworthy, and the brother-in-law of Lynn Redgrave, who portrayed Susan. Both relationships were due to Richardson being married to Vanessa Redgrave from 1962 to 1967.
The first 13 on-screen closing cast credits are under the heading "Squire Allworthy's House". The next 5 are under "Squire Western's House", then 7 are under "On the Road to London" with the final 3 under just "London".