A bullet fired into a wall achieves implausibly shallow penetration--the bullet base actually protrudes from the wall surface.
The photograph of Lowell, Hocksley and Carr standing on a day-lit Chinese street is faked, because none of the men casts a shadow.
Tragg finds the combination to a safe inside the cover of a pocket watch. He finds the dial on the safe set to the third number of the combination. He and Mason surmise that all he needs to do is turn the dial to the fourth (and last) number and the safe should open. Hé bends over, grasps the dial, pauses for a couple of seconds, then reaches for the handle, turns it, and opens the safe, never having moved the combination dial at all.
When Doris Hocksley is reading the newspaper ad, she mentions Elston Carr's address as 133 Remuda Dr -- yet in the establishment pan of Carr's estate, the address at the curb is 3972 -- the actual address of the home used in the stock shot.
In the opening scene of San Francisco, the stock footage shows a busy neighborhood of cars parked along the street with other cars traveling by. All of the vehicles shown are 1940s vintage models without any contemporary mid-1950s models as would have dominated society at the time.
After Perry finds the hidden photograph in the false bottom of the tin box, the judge calls for a continuance until the next day. As the judge starts to rise there is the sound of a striking gavel. The gavel is visible on top of the judge's bench.
The District Attorney calls the sergeant to the stand by calling Sgt. Bix while the sergeant's name is actually Dix.