In 1976 one of a party dignitary tells about opening a new Central Railway Station in Warsaw. This station was opened in 1974, not 1976.
When Gierek is transferred to the Anin Instituf of Cardiology because of heart attack, he is given in intravenous injection of Aspirin. Intravenous Aspirin is not registered in Poland and it wasn't recommended in heart attack in 70'.
After the first loan from western banks Gierek talks about the development of IT industry. The wasn't such an industry in early 70' in Poland.
When Marzena goes to her home, Pierre can see, that she lives in an apartment building on a residential estate of "greate plate" technology consisting of plates made in a factory of houses. Such factories started to produce plates in those years, but in that film you could see a whole estate ready in 1973 - even if it was one of the first "great plate" building, you couldn't see other elements of estate (for example big trees )