The missions and their background are largely based on real historical events of WW2. For example, one of the target persons in mission #5 (Paycheck), Major Andreas Meyer-Mader and the reason he should be killed.
The English localized version is censored. There are no pictures of real Nazi leaders and no swastikas, although this is not forbidden in the USA or the UK.
One of the target persons in mission #6 (Project Y) is Professor Charles Brown. This might be a reference to the famous cartoon character Charlie Brown from Peanuts