The length of Mrs. Peel's fingernails changes throughout the episode.
(at around 46 mins) The rifle and bayonet are in different positions then at 25:08 when no one touched the rifle and bayonet.
(at around 41 mins) Steed rams a closed road sign and damages the rim around the front right headlight. Seconds later (at around 48 mins) just before Steed drives over the jagged piece of metal his front right headlight has fallen forward. Seconds later again (at around 16 mins) after Steed stopped his car with 4 flat tires, Steed starts to walk and passes the front right headlight of his car which is back in its normal position.
(at around 50 mins) After Emma Peel cuts her picture. The slice in her photo is only a couple of inches apart but seconds later (at around 52 mins) the gap is now a foot apart.
(at around 48 minutes) When the rooms are spinning around Steed, his reactions are much more severe when viewed from the back then they are when viewed from the front.
Emma's key leaves a white shape on Steed's photos. Talking to Pongo on the phone, Steed says it has "electronic properties". Electric or magnetic fields haven't any effect on photographic film or paper. Radiation however would have left a black shape on the photo, but not a white one.
The punch-card slot is enormously too large to be real. They are about as thin as a punch card.
(at around 28 minutes) When Steed parks his Bentley, the camera zooms out from him, but the background projection remains the same.
Episode "The House that Jack Built", when the camera follows Emma Peel in the background and pans by the plastic dome in the foreground, close-up images of camera and crew can be seen in the rotating mirrors inside the dome.
(at around 55 mins) A crewman looking down can be seen in the reflection of the machine.
(at around one and a half minutes) When the prison guard passes close to the camera, the shadow the cameraman is visible on the guard's uniform.
Keller's image on the television screen couldn't possibly interact with Mrs. Peel's responses to it unless the whole thing was scripted.