Although the chorus consisted of British performers, they are all lip-synching to the American singers from the original Broadway production.
Kevin Kline won the 1981 Tony Award (New York City) for Best Actor in a Musical for "The Pirates of Penzance" Broadway 1981 to 1982 production and re-created his role in this cinema movie. It was Kline's second Tony Award after having won one for "On the Twentieth Century". Kline also starred in the precursor New York Central Park stage production and that park production's subsequent made-for-television movie, The Pirates of Penzance (1980).
In this version, several lines of dialogue and song lyrics have been changed to be comprehensible to an American audience. Thus "Can it be Custom House?" becomes "Can it be the Coast Guard?"
This movie's failure at the box-office had nothing to do with the reviews, which were often quite positive. The real problem lay with Universal Pictures decision to release this movie simultaneously to SelectTV and to theaters. Theater owners were so angry, that they boycotted this movie. In the end, a grand total of ninety-two theaters agreed to show it, and it enjoyed a long run at only one of them (in Washington, D.C., where it became a cult success and played several weeks).
In Act II, there is an extra song ("My Eyes Are Fully Open") that is not originally from "The Pirates of Penzance." It's a modified version of a song from Sir W.S. Gilbert and Sir Arthur Sullivan's "Ruddigore". The inclusion of this song required Kevin Kline, Dame Angela Lansbury, and Rex Smith to sing one of most dizzyingly rapid songs in the entire Gilbert and Sullivan catalogue.