Deliberate mistake: In the scene where the ministers are all crammed into the train carriage if you look over Jim's shoulder there is a sign ("Notice" "In case of Fire" etc), while the headers are in English the actually paragraphs are written in gibberish.
Yes, Minister (1980)
1 mistake in The Official Visit
Starring: Nigel Hawthorne, Derek Fowlds, Diana Hoddinott, Paul Eddington
Genres: Comedy
Bernard Woolley: That's one of those irregular verbs, isn't it? I give confidential security briefings. You leak. He has been charged under section 2a of the Official Secrets Act.