Goofs

Fay Wray's character is variously addressed as "Joanne" or "Joan," sometimes in the same scene.

When Lionel Atwill as Dr Xavier leads the plain clothes police detectives on a tour of his academy, he introduces them to Dr. Haynes, saying, "This is Mister Stevens and Mister O'Halloran. They're making a tour of scientific research." Haynes suddenly takes Atwill aside and says with alarm, "Why did you bring the police in here? Get them out!", but Atwill had made no mention to him of their being policemen.

As Dr. Xavier displays the wax figures of the murder victims, on the first figure, that of the "woman of the streets", the left hand can be seen trembling slightly.

None of the cars driving "at night" by the waterfront have their headlights turned on.

Although he supposed to be a medical doctor, Dr. Xavier mispronounces "scalpel."

In the opening scene of the film, Lee Tracy is shown strolling along the New York docks in search of news, when a body arrives at the Mott Street Morgue across the street. In reality, Mott Street, located in New York's old Chinatown district, is fairly well landlocked and nowhere near the either waterfront or dock areas.