Factual error: Why is Hilts not wearing a uniform? A serving officer captured behind enemy lines in civilian clothing risked being shot as a spy. If a prisoner's uniform was too worn or damaged to wear, it was routine for the German authorities to replace it - a P.O.W. in civilian clothes is an obvious escape risk. He is wearing a pair of tan chinos, a cut off sloppy Joe sweatshirt, both ridiculously anachronistic - Sixties hipster fashions - and nowhere even close to a World War 2 uniform. He is also wearing Army Type III Service boots - something that would never have been issued to a fighter pilot.
Factual error: Twice in the film it is made clear that the Pym particle works by reducing the space between atoms in order to shrink an object, and by increasing it to enlarge them. This means that the object will weigh the same, whether shrunk or enlarged - it cannot be otherwise. A 90kg man the size of an ant would punch a hole through any surface upon which he stood (and couldn't ride ants), Doctor Pym has been walking about with a 60 tonne tank in his pocket, Darren Cross lifts a full grown sheep between finger and thumb, and the supersized Thomas The Tank Engine would be far too light to crush the police car (in fact it would float harmlessly away as it would probably weigh less than the air it displaced).
Continuity mistake: In the British Museum, when Rick and Ardeth are saving Evie, Rick gives her a .45 pistol and they start to shoot the guards, her pistol fires once and the slide locks back meaning the pistol had no ammo, but she keeps firing as if the magazine was still full. (00:39:47)
Revealing mistake: During the bedroom scene with Felicity and Fat Bastard you can clearly see the air hose that fills his suit when he rolls over in the bed. (00:49:10)
Continuity mistake: In the final battle, Wasp and Ant-Man are in the van trying to get the quantum tunnel operational. We cut back to the fight and we can see Ant-Man there too, fighting in his giant form. (02:22:20 - 02:23:00)
Revealing mistake: There are supposed to be two dead young Asian males sitting in the back of the car, but in this shot, it is so obvious that there are two dead 'dummies' riding in the back. Also, in the crash, a few seconds later, very blatant dummy heads are flying everywhere. (00:40:40)
Other mistake: Fireworks use heated metals to produce the various colors seen when they explode - Iron, Nickel, Cryolite, magnesium and copper filings. Flying a jet engine through exploding fireworks would cause serious damage to the engine.
Factual error: Trevor - a Professor of Geology - boasts about having an article published in Scientific American, and that is not something any scientist would do. Scientific American is looked upon with slight disdain by the scientific community, considered to be a populist crowd pleaser. It is not even peer reviewed. Considering that he has just turned the geological and archaeological worlds on their heads he would have been better off publishing in Journal of Geological Research or Geology, both prestigious professional journals.
Other mistake: Murphy lands the helicopter on a railway line so an oncoming train will destroy it completely, and this happens exactly on cue with huge, dramatic explosions and flying debris. Apparently the train driver doesn't think this is important enough to interrupt his busy schedule - he doesn't stop the train. We do not hear brakes being applied - the wheels would make a noise like the sky coming down - and the train doesn't slow down at all - it just keeps on going.
Continuity mistake: On the ferry, Rachel wears the purple/pink camouflage hoodie over her orange knit sweater with the colorful stripe sleeves, as usual. Now this is where things become strange. In the first shot as the trio come ashore, she is only wearing her orange sweater, she is not wearing the purple/pink hoodie - note the clear lack of fur hood. In the very next shot as they climb a bit more and then rest, Rachel is wearing the purple/pink hoodie - note the hood, but now it's on under her orange sweater. In the underwater shots she is also wearing it under the orange sweater. (This odd mistake has absolutely nothing to do with the very long wool cloak that Rachel wears in the next scene). (01:02:20 - 01:04:40)