The elastic band across Arietty's chest disappears when she slides down the downpipe, but reappears when she meets Spud Spiller.
When Pete comes into the dairy to save the borrowers, he sees five borrowers taped to the machine; however, this was after Potter removed Spud and dropped him in the engine.
The film is set in a fictitious time and place which include elements of both Britain and North America, technology and products from many different eras, and fictitious uniforms and currency.
Although the film is set in "a fictitious time and place", they are driving on the wrong side of the road. When we see an aerial view of the streets, the junctions are marked out for driving on the left-hand side of the road UK style, but the cars are driving on the right.
When Arietty and Peagreen travel along on the telephone wires how did Potter's bloodhound track them?
How does Potter's car suddenly turn up at the bakery?
How does Potter know how to operate the machinery in the bakery?
When Spiller throws the rope in the milk bottle trying to pull Peagreen out, he can be heard straining and grunting to keep a hold of it but his face and mouth are both clearly relaxed.
When the insecticide foam is removed from Potter's face, it has burned off his moustache, however it covered his face and his fringe, yet it hasn't burned off his eyebrows or any of his hair.