Corrected entry: In some scenes, barcodes are visible on cola cans - barcodes weren't around in the 60's.
Corrected entry: When Paul McGann leaves Uncle Monty's cottage to buy food and firewood from the farmer on the first morning of his 'holiday', he is wearing nothing but underpants underneath his raincoat. However, less than a minute later he is wearing a pair of dark trousers and a red jumper as he approaches, and climbs over, a locked gate. (00:37:25 - 00:38:15)
Correction: Not a continuity error - time has passed for Marwood to get changed before visiting the neighbouring farm.
Corrected entry: In about the penultimate scene of the film, Paul Mcgann packs his suitcase ruefully, placing a copy of 'The Adventures of Huckleberry Finn' on top of his piled clothes. On the paperback's cover, there is a sophisticated reproduction of a painting of a steamboat. Such printing techniques were far beyond the capabilities of Penguin Books at the time the film is actually set, when the standard cover would have comprised a series of white and green/orange bands.
Correction: Not true. The other book was Huysman's Against Nature in the black 60s Penguin Classic edition which had a pictorial cover. This was right for the period. If there was a continuity mistake it was that the other book was an 8vo yellow black Penguin Classic, a series that wasn't introduced until the 80s.
Corrected entry: Withnail's car is an ancient, battered, rusty Jaguar which looks about 20 years old. However it is H registration and so would have been brand new when the film is set.
Correction: The car's number plate is '405 SBH', meaning it predates the number plate system, and therefore would be pre 1961. The car was made from 1955 so could be as old as that.
Correction: Not true. There have been a variety of systems in place since the late 1940s and what we know now as a barcode reader has been developed from these. The online encyclopedia 'Wikipedia' (should it be believed) gives a long and 'interesting' description about the development of barcodes - it is shorter to refer to that than to list it here! http://en.wikipedia.org/wiki/Barcode.