Goofs

As Scott is watching the fog approach, his hairstyle changes between shots.

When Scott brings the lampshade to the ground, the lampshade cover falls upside down. Between shots it appears to be turned on its side.

When Scott approaches the bird behind the wire mesh, he is holding the piece of cake with his left hand. Next shot the piece of cake is in his right hand.

In the first shots of Louise relaxing on the boat, her left leg is bent with the foot about even with her right knee. It then cuts to a closer shot and the foot is closer to her right ankle.

When the doctor is injecting Scott with serum the needle appears to be proportional to Scott's arm when it should be much larger.

Even though the spider in this film is clearly a tarantula, it is shown sitting in a standard spider web. Tarantulas do not build webs like that. They live in burrows or holes.

When Scott is pushing on one side of the cellar door and the cat on the other, the cat is so much heavier than Scott that it would have no difficulty pushing the door open.

Although Scott Carey grows increasingly smaller, the pitch of his voice never changes. The pitch of a person's voice is primarily dictated by the size of the vocal chords; as he decreases in size, his voice should have increased in pitch, eventually becoming inaudible to human ears.

At a certain point Scott should die from being unable to breathe, as the air molecules would have got too big for his lungs to process.

Shrinking from 6 feet to 6 inches means a scale reduction 1:12 which means that volume and weight reduces in a scale 1:12 cubed. If a 6 foot man weighs 80kg the shrunk version would weigh 46 grams. He should have moved much faster. In the cellar he is about 3 inches and he weighs about 2 grams. He should have climbed with no effort. In addition, he says when he is 3 feet tall that he weighs 52 pounds. A child that tall may weigh that much but under the square cube law, a 180 lb, 6 foot tall man should weigh 23 pounds at 3 feet (divided by 2 cubed or 8)

After Scott struggles across the paint stick, it collapses. Later, he descends from the top of the crate down to the floor again, but it is unclear how he made it, as the paint stick had fallen. It is later shown that he is able use his bent pin and thread to walk on the paint can ledge, so he may have used this method at that time as well.

When Scott is standing at the top of the cellar stairs, calling down to his wife, the picture on the wall behind him is clearly visible through his body.

When Scott is crossing the hole in the crate by holding onto a rope and walking on the ledge of the paint can, the extra rope that should be hanging in the hole stays horizontal, revealing that the hole is, in fact, not a hole. It is especially visible when he gets to the other side and pulls back the rope towards him.

Look carefully when Scott is running from the cat and from the spider. In the close-up shots Scott has a shadow. In the long-shots he has no shadow because he wasn't really there, he was just placed on top of the film.

After Scott and Louise argue in the living room and she leaves, a line running from the rug to the table legs is visible on the floor. This is the edge of the forced perspective set.

As Scott goes out into the night to the diner, people walking around cast shadows on the ground. Yet, Scott casts no shadow at all.

Scott first notices his clothes getting bigger six months after passing through the mist on the boat. Later, while talking with one of the doctors he recounts having been accidentally sprayed with insecticide "about two months ago", which the doctor then states was already in his system when he was exposed to the mist.

When Scott is living inside the matchbox, there is a light source inside casting his shadow on the wall..