The German tank destroyer often used by the main characters in this movie actually is a Soviet-made SU-122 self-propelled assault gun.
[It is actually a Russian made SU-100 tank destroyer; the SU-122 had a short barrel 122mm that fired a High-Explosive (HE) round).
In the guardroom there is a poster with V and Viktorija. The film was made in former Yugoslavia and perhaps they couldn't find a poster in German (Seig). Also V on a Russian train? Z for Za Pobedy in Cyrillic would be like 3 in Latin script.
The SS stopped wearing the black uniform before the war started. They should have been wearing a field gray uniform.
The tank that the misfits arrive in at the beginning of the film is a Soviet T-55 model, considerably post-dating the Second World War.
In the 28-min mark, one of the German tank crew refers to a KW-2 Russian tank. He probably meant KV-2.
Towards the end of the film, the German general (Oliver Reed) orders "Get some flak up." No German would say this. Although to the western allies "Flak" meant aerial shrapnel, to the Germans it meant the gun that fired the shrapnel. It is an acronym of FLiegeAbwehrKanone, which simply means anti-aircraft gun.
In the novel it is Josef Porta and Capt Von Baring.
The fight between Tiny and the Legionnaire takes place in "Comrades of war" also the character of Freckles is not in the novel.