Democrats have tried to shine light on these and other scandals using what are called “resolutions of inquiry,” which can tee up what are essentially special votes over whether to provide information from the president or executive officials.
These cards were used in Italian national elections in 1929 and 1934 when Mussolini's party was the only legally permitted party. Voters (at the time, only males who were trade union members, clergy, or soldiers) could only vote to approve or disapprove the list of deputies the Grand Council of Fascism had appointed. The officials would check that the card the voter chose was properly sealed, so the colors would probably immediately let them know which vote is being cast. And/or it was propaganda: voting for yes is patriotic, and no is... less patriotic.
The Acerbo Law gave 2/3 of the seats to the party that got at least 25% of the votes. After that every election was a plebiscite in which you could only approve a list of candidates from the fascist party