Goofs

When Dr. Kassel is brought into the FBI office for interrogation, he has a white handkerchief tucked inside his suit's breast pocket. When it cuts to a close up of Dr. Kassel sitting down after the confrontation with Hilda Kleinhauer and talking to Renard, the handkerchief has disappeared and stays missing for the remainder of the scene. When Dr. Kassel returns to his office, the handkerchief reappears.

There is a large sign on a fence reading, "Fort Wentworth Base Hospital". The Army does not refer to its installations as "bases". A correct sign would have read "Post Hospital".

According to the film, the spies are allegedly working for "German Naval Intelligence". In reality, no such agency existed. The Abwehr was the joint intelligence service that coordinated foreign espionage for the entire German military. Before and during most of WWII, the Abwehr was headed by Adm. Wilhelm Canaris. Also, Canaris and Heinrich Himmler, the head of the SS, detested one another and would never have cooperated as shown in the film. (The producers may not have known this in 1939.)

The private who helped Schneider obtain classified information is tried along with him and the other spies. As a serving member of the military, he would have been tried by a court martial.

When the boat is leaving America, it is going right to left with the Statue of Liberty in the background. This looks as if it is just arriving, as if it were leaving, it would be going left to right.

Back in Germany, Kassel attends a camp gathering in the country. His party in 3 cars drives under a banner proclaiming 'Welcome Home Dr Kassel', but this is facing the camera so he wouldn't see it.

With a train speeding along tracks and under a signal gantry, the narrator says, "Arriving in Germany, Dr. Kassel finds a totally different Fatherland from the one he left 10 years earlier." However, the engine, the carriages, and signals are all obviously British.

At the 00:21:00 mark when a fight breaks out at a Bund meeting the audio sounds as though there are many women screaming but there are actually very few women seen there.

Early in the movie on board the ship, when a telegram is brought to a Nazi meeting, the swastika on the arm band of the guard to the right is backward.