Character mistake: When John Henry Irons is arrested, two police officers lay him face-down in order to zip-tie his wrists behind his back. A close-up of Irons' hands, however, reveals that the zip-tie only wraps around his right wrist while crossing about mid-way on his left thumb, meaning that he could easily remove his left hand from the restraint with very little effort. Arresting police officers would never make this mistake in real life.
Character mistake: The Daily Planet newspaper headline "New publisher for your favourite paper" has "favourite" is spelled the British English way. Since Metropolis is in the United States it should be spelled "favorite."
Character mistake: When Harry takes the kids to his business, he's showing them how he "restores" cars. After putting the bumper on, Harry says, "Transmission. The sawdust quietens the gears and let's the engine run as sweet as a nut." Putting sawdust into the transmission would not change how the engine runs as they are two separate components. It may make the transmission quieter but would have zero effect on the engine.
Character mistake: Flynn has been reading for a while, taking notes, spreading books around, etc. - when Nicole arrives and says that it was nice to watch take-off from the cockpit. The plane must have been in the air for a long time by then.
Character mistake: In a scene on Johnny Whitefeather's patio, his son is referred to as a "ten-year-old boy." Later, in a business meeting, Whitefeather says his son is nine.
Character mistake: When Béatrice checks the historic book,Godefroy is born in 1076,but later in the film,Godefroy says that he's born in 1079.
Character mistake: During the scene at the office of the University of Oxford, the Union Jack is hanged the opposite way from the proper position. (01:23:10)
Character mistake: At the end of the movie, when Jaggu is listening to the sounds recorded by PK, the audio contains the question which she asked, "Tumhare planet pe sab aise hi hote, bade kan wale?" but does not contain the answer which PK gave, even though he was sitting right there. This seems to suggest that PK did not exist in the real world.
Character mistake: A priest is holding a globe with a fire to light the globes carried by others. There are two lines with globes approaching the man with the lit globe. The first person in the line from the right has trouble lighting their globe. She starts to return for a second try, but apparently thinks better of it and continues on with the unlit globe.
Character mistake: At the beginning of the movie, Marnie states that she is 13 years old. When Grandma Aggie comes to visit, she tells Mom that it is Marnie's 13th Halloween. Since everyone celebrates their first Halloween before they turn one, if Marnie is 13 the events of this movie would occur on her 14th Halloween, meaning her powers would have faded by now.
Character mistake: There are signs out front as the Spenglers arrive at the dirt farm. One of the signs is a call back to a scene in Ghostbusters 1984. In the scene, Ray quotes the book of Revelation: "And I looked, and he opened the sixth seal, and lo, there was a great earthquake. And the sun turned black as sack cloth, and the moon turned blood." When Finn Wolfhard reads it he misquotes the line saying "The sun became as black as cloth."
Character mistake: When Inspector Owen calls the village police station the call is answered by a sergeant but at the end of the call Inspector Owen refers to him as Inspector. (00:10:00 - 00:11:00)
Character mistake: When Darcy walks into the police station the chief calls her Joan, the lead actress' real name, by mistake.
Character mistake: When Charles comes down to breakfast the evening after Elvira arrived, he comments to Ruth what a wonderful day it is, "not a cloud in the sky." But that's wrong; there's a low cloud bank and the rest is murky and gloomy.
Character mistake: Henderson asks the guy as he's leaving the room to get him some bourbon. They already drank in the bar and spat it out when they found out that everything had turned to blood, so it would still be blood.
Character mistake: Big Ben is loaded feet first into the ambulance, he should've been loaded head first.
Character mistake: When Brenda first witnesses Connor and the Kurgan fight, Kurgan says "I am the only one." Afterwards, Brenda asks "What does he mean by there can be only one?" She somehow misheard Kurgan and thought he said the movie's iconic catch phrase.
Suggested correction: This is incorrect. He does say "There can be only one." He's saying it while beating Conner, so the first part is a little muddled and he emphasizes "one", but he does say the line.
Character mistake: At the beginning of the movie, during "Provincial Life", we see a fat lady trying on a hat in a hat store. The sign over the window, in French, reads "Chapeau" (hat). The correct way to identify that store would have been "Chapeaux" (hats) or "Chapelier" (hatter).
Character mistake: Tom states that the Republic of China released fifteen American POWs in 1955. The People's Republic of China (Communist China) might have done so, but the Republic of China (Taiwan) has always been an American ally and would not have been holding any Americans prisoner to begin with.
Character mistake: When Duddit's mom is packing his lunchbox, she refers to him as "Henry". (01:45:54)