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.
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.
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.
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.