It says "The film is set in 1877, but characters talk about the Turkish spy Enver Pasha, who was born in 1881". The name of the spy is "Enver Bey" simply means "Mr. Enver", he is not "Enver Pasha" this famous historical figure.
Actually, the spy in the movie is Enver Pasha, and is referred to as "Enver Pasha" :-) You're mistaken with Ismail Bey, the Turkish army general portrayed by Gosha Kutsenko.
"Our great war is a spiritual war. Our great depression... is our lives!" - Tyler Durden.
The spy is not Enver Pasha. He is some other Enver. They refer to him as Enver Bey. He is never addressed as pasha.
Also the adjutant of Osman Pasha during the Battle of Plevna was not Ismail Bey. Ismail Bey was Osman Pasha's adjutant after Pasha was returned from Russian captivity.