Anachronisms: Arthur constructs an irrigation system using split bamboo and plastic "Bendy Straws". In the 1960s, drinking straws were made of waxed paper.
Factual errors: Arthur visits the Minimoys just after midnight on 1st August 1960 because it is the full moon just after his birthday. The actual full moon date was 02:43 (UT) on Sunday 7th August 1960.
Anachronisms: The story takes place in 1960. Arthur's toy car, a Ferrari 250 GTO, debuted in February 1962.
Continuity: When Granny hangs up the lite lamp on the porch, she is unable to reach as its too high. Then the next scene, and another later, she is able to reach it.
Errors made by characters (possibly deliberate errors by the filmmakers): Selenia is surprised Arthur knows her name when they first meet, but her father just named her to the whole audience.
Continuity: In the end credits, humans in Minimoy form only have four fingers like real Minimoys, instead of five like Arthur and Archibald.
Continuity: Selenia harpoons the poppy on the outside. When she pulls it down, the harpoon is on the inside.
Continuity: Minimoys size (2.5mm) is not consistent through the movie: bigger when in the straw, smaller when Arthur runs under an ant, much bigger when dancing on the vinyl disc, bigger on the model car, bigger on the ruby pile etc.
Errors made by characters (possibly deliberate errors by the filmmakers): When Arthur needs a rope and asks if Betameche would have one, Betameche says that he hasn't got any rope. In the next scene, when Selenia takes Betameche's Swiss army knife, he has a rope.
Anachronisms: When Arthur is dancing they play several songs (Let's Dance and Stayin' Alive) from the 70's even though it is only 1960.
Plot holes: At the beginning of his journey, Arthur is told he has 36 hours to complete his task or the doorway between the worlds will close for 1000 days. Later, he mentions that it will be ten more moons until he sees the princess again, when 1000 days amounts to just less than three years.
Anachronisms: While driving in the tunnel Arthur says he hope there are no speed cameras down there, but speed cameras wasn't invented until 1989.
Anachronisms: "Theme From S'Express" is heard on the soundtrack. This was a 1988 hit, in a movie set in 1960.