Size inconsistencies in a film in which people are shrunken down to a tiny size. For example, the rat is larger than people, but also larger than a car tire.
The saucer of milk used to lure the cat into the lab changes position on the window sill between shots.
When Franz goes from the front room to the rear, he exits on the left side of the doorway, as viewed from the front room. When the shot immediately cuts to the rear room, he's shown entering on the opposite side of the doorway.
When Franz leaves the room because of the visit of his friend, the teen boy lassos a string on the door knob. When Franz comes back, he climbs down and the string mysteriously disappears.
The teenage boy unhooks the string from the door knob before running back to join the others.
When miniature Sally and Bob sneak out of the theater they open the stage door and there is a bottle laying next to the door.
When Mr. Franz follows them out the same door the bottle has disappeared.
Movie title "Six Inches Tall" the subjects are clearly much larger than that, perhaps 10 to 12 inches tall. This size inline with models Franz has on display.
Although the actors take great care to ensure, when handling containers with tiny humans inside, that they are always facing the camera, sometimes they get it wrong, revealing that the figures are flat photo cut-outs.
About 18 minutes in, the main couple are watching a drive-in movie and it is obvious they are on a soundstage because the surrounding cars are just pictures/paintings.
When Mr. Franz is explaining his shrinking method, his hand goes behind the projected image instead of casting a shadow on it.
"Sergeant" Paterson is wearing corporal's stripes. A sergeant has three stripes whereas a corporal has only two. Paterson is wearing only two stripes.
When the puppet people are put into the suitcase for the trip to the theater, they are laid down horizontally. But the puppet master picks up the suitcase and carries it vertically, which would then toss all the puppet people all over the inside.
At the 18 minute mark as the camera moves in it throws a shadow onto John Hoyt's right shoulder..