When Mervyn and Kopernick are playing tug of war with the script and it tears; Mervyn falls down and is left with the shorter piece of the script. However in the next cut when Mervyn gets up and threatens him; Mervyn is now holding the bigger chunk of the script.
When the Inspector is looking at the various newspapers in the commissioner's office he grabs the top paper (Evening Standard) and brings it back toward him and away from the next paper in the pile (Daily Herald). However, in the next cut, he is now holding the Evening Standard with his left hand hovering over the Daily Herald. The orientation of the papers continues to change in the following cuts.
When Woolf finishes talking to the Inspector and then walks away back toward Spencer and Mervyn; he stops and stands behind Mervyn. However in the next immediate cut; he is in the middle of again walking toward them and once again stopping next to Mervyn.
When the Inspector and the Constable first enter the dressing room, there is a ski and broken pottery pieces on the floor. However, in the next cut when they move past the ski and look at the dummy; the orientation of the ski and the shattered pottery pieces have changed.
When the Inspector is in the Commissioner's office; he has both hands clenched behind him and holding his hat. However in the next cut when Stalker brings in the newspapers; he now has both hands separated and uses a handkerchief being held with his right hand to nurse his nose.
At 24:51 a torn play script is shown with both the bottom and middle holes filled with brad fasteners. It is an unwritten rule in the industry to never affix a brad in the middle hole, and is seen as an indication of a lack of professionalism or at least a lack of experience.
At 27:53 an illustration of a Lee Enfield rifle is shown, but the artist mistakenly drew it with a left-handed bolt action. No left-handed Lee-Enfield rifles were ever made.
At the end, Inspector Stoppard is awarded the King's Medal for police etc. This movie is set in 1953; while Queen Elizabeth ascended to the throne in February 1952, the name of the King's Medals were not changed to Queen's Medals until May 1954, so it is accurate that the award Stoppard received would be called "King's."
When Leo is drinking from the whiskey bottle and about to fight the husband of the woman he is flirting with; the film does a split screen of the exact same action with different angles. However, the action on the two screens is slightly different indicating that they used different takes for each split screen.
When walking to Kopernick's room in the Savoy, the reflection of upcoming lights can be seen on the chest of Pierre. Potential clear screen in front of the actors between them and the camera.
Commissioner Scott refers to the murderer at 10 Rillington Place as a "serial killer", a term that wasn't coined until the 1970s.
Morris Minors weren't used by the police until 1956. The film is set in 1953.
The Morris Minor police car that Constable Stalker used in the later part of the movie had a pale blue and white colour scheme that was only brought into use in 1967.
Also, the car is a later model Morris Minor with enlarged front and rear parking lights and turn signals.
Also, the car is a later model Morris Minor with enlarged front and rear parking lights and turn signals.
When the characters are looking for each other in the theatre, the self door closers are of a modern rectangular design, not the bulky cylindrical design of the 1950s period.
Some of the dialogue is strictly 21st Century; e.g., assistants were still called "secretaries" back then.
A banner says "Wallingford, Berkshire" but Wallingford is in Oxfordshire.
Wallingford is in Oxfordshire today, but in 1953 it was in the county of Berkshire. This was the case until 1st April 1974 when the county borders changed and much of North Berkshire became part of Oxfordshire.