When Nancy and her father get to the house in the country, from the outside the blind on the door covers only part of the top panes of glass. But, in the next shot from inside, it's below the top two panes. Also, from outside the panes are rectangular and from the inside they are square.
in the airplane scene, you can see the wires coming out of the front and back of the plane as it's seen "hopping" over an obstacle near the ground.
The telegram Nancy receives states Sylvan Lake is in Wisconsin, however several palm trees are visible and from aerial shots the topography is obviously that of Southern California.