A different Amiga version of the game exists with invading extraterrestrial aliens being the culprit, instead of German Nazis. This is a localized version for Germany, where references to Nazis and swastikas were not allowed in video games at the time, not even as antagonists. However, the original designs were retained, which raised logical questions about why aliens would adopt German WW2 technology and be largely successful with it. This version was also the basis for the NES port, due to Nintendo's strict content restrictions at the time.
Source: Wikipedia, "Rocket Ranger", available under the CC-BY-SA License.