In reality, Lady Caroline Lamb was addicted to laudanum, which is generally thought to be one of the contributing factors to her premature death. There is no reference to this specific addiction in the movie, although in the first scene Lady Bessborough offers Caroline a tincture of some sort for her nervousness, that tincture which most-likely is laudanum.
Timothy Dalton was contracted to play William Lamb in this adaptation, but was replaced at the last moment. Dalton sued the production company for breach of contract and won.
This movie's critical and commercial failure dissuaded Robert Bolt from ever directing again and, some say, also led to the break-up of his marriage to Sarah Miles. Bolt and Miles remarried in 1988, the union lasting up until Bolt's death in 1995.
Lord Byron (Richard Chamberlain) was not as tall as portrayed in this movie, and suffered from a limp.