In the "pacing" scene, as Quell goes from wooden paneled wall to window and back, the second time he goes to he wooden paneling, he breaks out a panel when he pounds it with rage. In the numerous successive shots, the wood panel is restored.
At the end of the first "processing" scene between Master and Freddie, the ashtray switches from empty to suddenly full of cigarette butts.
When Freddie starts undergoing processing at Helen's house, Lancaster Dodd has a handkerchief in his left hand but as the camera switches to a different angle, the handkerchief has shifted to his right hand.
Although some of the nurses in the hospital scenes could have been at a V.A., the doctors could not. The V.A. is not staffed by military, and the doctors do not wear military uniforms.
At the beginning of the film, when the end of W.W.II is announced (August 15, 1945), the U.N. is mentioned. The U.N. did not yet exist. It was established October 24, 1945. Additional Information: During WWII the allied nations (Great Britain, Canada, Australia, USA etc.) sometimes also were known as the United Nations, so this identification would have been possible.
Both Lancaster Dodd and the Judge referred to the ship that took them from San Francisco to New York as a "Sailing" Ship, where it clearly has no rigging to support Sails,... it is a Motor Vessel (MV).
When Freddie kicks and breaks the toilet in jail there is no water in the bowl or spilled onto the floor, or visible on the floor in subsequent shots.
When Freddie first goes to Doris' house, there is a motion-activated spotlight on the house next door as he is climbing up the stairs. Motion-detecting lights weren't introduced until 1985.
When Freddie is first seen visiting Doris' house, aluminum stick-on numbers are visible in the establishing shot, giving a street number. These numbers didn't' come onto the market until the 1960s.
The catch wiring on the side of the ship when the men were relaxing they didn't match 1950 ships. They were made of some kind of synthetic wiring. That technology wasn't available at that time frame. Even today they still use metal wiring on those things.
When Lancaster Dodd is challenged by a skeptic, the shadow of a boom microphone is visible on the wall behind Dodd.
The architectural style of the house where they stay in Philadelphia is known as California craftsman, which is not found anywhere in or near Philadelphia.