The film's copyright date is given as MXMLXXIV. It should be MCMLXXIV for 1974.
In the opening credits (~00:01:30), the Roman-numeral representation of the year of production (1974) is incorrect; instead of MCMLXXIV, it is given as MXMLXXIV.
Although set in London in 1946, double yellow lines and television aerials are clearly visible and an overhead view on London shows motor vehicles for the early 1970's.