When Mr. Moto photographs Gloria in Honolulu, she is looking directly into the camera, but when he shows the photograph to the police chief in Shanghai she is looking away from the camera at Bob who is obscuring half the photograph even though he was standing beside Mr. Moto, not in front him, and thus should not be in the photograph at all.
When Gloria is skeet shooting at the edge of the boat, she cocks the shotgun and the spent shell is seen flying through the air over the side of the boat into what should be the water down below. Instead of hearing a splash, the shell is heard bouncing on what sounds like concrete (stage).
That is an obvious stuntman demonstrating Mr. Moto's jujutsu in Bob's cabin.