The initial American release had many cuts made to avoid upsetting some special interest groups. the running time was cut from 123 minutes to 104 minutes. Most of the submarine's voyage up to Hudson Bay was removed. They dive after sinking the freighter (and filming her crew) and we next see them in the Bay, preparing to send the raiding party ashore. All the scenes of them entering the Bay, including the reference to "his charts" (the missionary's), were cut. They cut all references to the "flying missionary" who was a German spy, the scenes with the map and all of it. They also cut the other "delicate" passage there, where Hirth tells the captive Canadians that the Eskimos are sub-apes like Negroes, only one step above the Jews, and the ripostes from Johnnie and the Factor. Obviously they didn't want to offend southern segregationists or anti-Semites by showing that Nazis shared their racist views, or leave in any dialogue decrying same.
They also cut the montage of the Germans working at the Hutterite settlement, and a bit from Hirth's zig-zag escape after Banff Park -- the part with him aboard the airplane and its attendant radio report, though the rest of the scene is left in.
In the American edition, just as the German raises his arm to strike the motorist with the flat tire, and he begins to suspect that something's about to happen, the picture fades to black, but the scene does not stop: the sounds of the motorist being stuck, of him crying out, collapsing as his dropped soda bottle breaks on the ground, all are heard -- but it all goes on "underneath" a black screen.
The original film shows Hirth standing in a crowd in the rain while a woman is reading the latest bulletins to the blind soldier; meanwhile the other two sell their binoculars for money to eat, after which Hirth tells them of his plan to walk to Vancouver to catch a Japanese freighter home, based on his visit to a travel bureau. But in the American film, the entire scene after the news bulletin part is cut out, which leads to an enormous amount of confusion. Until then the Germans had been making south for the US border; suddenly, with no explanation, they're shown hiking along the road headed west, only a few miles north of the border. (The overlaid maps confirm this.) This made no sense whatsoever, and until we finally saw the complete film it was the major lapse in the film's progression.
The opening credits in the American version show, not the mountain ranges of Canada, but an extreme close-up of a beach: at first the sand is untouched; then as the title THE INVADERS appears, the shot dissolves into one of a boot-print in the sand, pointed ashore.