Location scenes of Nazi Germany were originally set to be filmed in Romania, but were canceled because of political instability in that country. Second choice was Hungary, but weather conditions during winter were judged too harsh for filming. Eventually the "location" footage was shot on the back lot at Universal Studios.
Six-Shooter was originally going to be a six armed ninja but was changed to a cowboy since the writer was a big western movie fan and it also made sense in the story as Six-Shooter would represent an American. The artist who created the poster used a 1988 Teenage Mutant Ninja Turtles Foot Soldier toy as a base for Six-Shooter. There was a ninja puppet in Puppet Master: Axis of Evil.