In the opening scene, a man enters the room with shaving cream on his face. He changes the disc on the record player and leaves the room. Seconds later, when the case is grabbed, he returns but the shaving cream is gone.
When Steed is first introduced to Sally Graham, she is wearing black dance shoes. Sally leaves the room with the case and when she reappears she is wearing brown outdoor shoes. After the fight between Tara and Audrey, Sally is once again wearing her black dance shoes.
When Tara and Captain Andrews set off in the red bubble car, the wall behind them contains the radar and communication equipment. Yet as they crash out of their lair, it is clearly totally empty.
When the musician enters his apartment, he picks up a trumpet and places the case on a red chair. The case is positioned so that the speaker grill is facing away from the camera. The musician sees Steed and as they fight, the case is untouched but it has turned around so the speaker is now facing the camera.
When Captain Andrews drives the bubble car out of the hideout he is wearing a trilby hat. When Trent crashes his motorcycle Andrews is wearing a bowler hat.
Mother states that the chain of couriers have been using the system of passing on the case for eighteen months, but the Cunningham family vault contains skeletons of deceased couriers. It takes many years for bodies to decay to skeletons and certainly a lot longer than eighteen months.
The case gave instructions to be left at King's Cross station at precisely 8am. When Tara and Steed deliver the case, the electric clock (which cannot be stopped) reads twenty to four.
When Steed fights the musician, both stunt doubles are clearly obvious.
Tara's stunt double clearly evident at the piano as she fights with Audrey.
When Steed appears for the first time, he comments that it's a beautiful day, suggesting that he had been elsewhere. As he enters the scene, his footsteps sound very clearly yet prior to his entrance, there were no approaching footsteps which means that Steed was on set all the time, hiding behind the scenery waiting for his cue.
At the airfield Captain Andrews warns of an intruder coming from the north-west, yet the Radar display shows that the intruder is coming directly from the west, not north-west.
According to the x-ray of the red briefcase, the speaker is at one of the corners. The slits for the sound, however, are in the center of this briefcase.
After the railway station connection, one of the contacts carries the case to a red mini. The interior light is on before he opens the driver's door because the passenger door is open to allow the camera to view the interior.
Crash mat visible at bottom of screen as motorcycle rider lands after being knocked of his bike and being hurled over the car.
After the case has been delivered for the final time, Mother is visibly distressed as this has cast suspicion on him as the villain. However, in the first conversation that Mother has with Colonel Stonehouse, Mother clearly acknowledges that he is fully aware that he is the Number One Suspect.