Mussolini was nominated by two different people. One of the letters of recommendation came from a German law professor while the other was from a professor in France. These letters are usually kept in the Nobel Institute archives, but these particular missives are missing. Consequently, the reasoning behind this nomination will never truly be known.
In 1939, Hitler was nominated by E.G.C. Brandt who was a member of the Swedish parliament. However, Brandt did not actually nominate Hitler because he believed in what the Führer stood for. Instead, the nomination was a protest against the nomination of British Prime Minister Neville Chamberlain that year.
In the years after WWII, other strange nominations would occur. The most confusing would be the two nominations for Joseph Stalin. The former leader of the Soviet Union was nominated first in 1945 and again in 1948.