The female agent from "O" who leaves a trail of clothes for Matt Helm to find apparently came with two sets of shoes; one that Helm finds among the other articles of clothing she has shed, and the other that she is wearing when the camera pans up on her in the bathroom.
During the car chase, Gail Hendricks can be seen sitting much closer to Matt Helm in the shots inside the car compared to the shots from outside (behind) the car. Also the front seat is significantly different when seen from outside the car. It is a bench seat with headrests.
Optical Special Effects error from 91:02 to 91:08 regarding the Allied Van Lines truck, supposedly with a helicopter inside. Unfortunately when the helicopter appears to be mechanically raised upwards from inside the truck, the incorrect background behind the helicopter of the blue sky and the fluffy white clouds also is mechanically raised upwards from inside the truck. When the helicopter flies away, the actual landscape of rocky and sandy hills, is seen behind the Allied Van Lines truck.