Corrected entry: At the beginning, when Tess is reading aloud facts about Mr. Twain, she says he was born in 1906. At the dinner table, Twain says he is 76 years old. This constitutes the date being 1982. Judging from the vehicles and clothing worn by the actors, the movie is set earlier than the 80's, probably the 50's or so.
Corrected entry: When Lionel Twain makes his appearance at the dining table he presses a button on his wheelchair which makes all the windows and doors become locked and barred. Then in a later scene when the group have returned to the lounge Dick Charleston opens the window to see if it has stopped raining but the windows are supposed to be locked and barred.