Factual error: Towards the end of the movie, two characters finally make it to a Louisiana sheriff's office. The sign out front reads, "Vierge County." There are no counties in Louisiana, only parishes.
Factual error: The morgue is located on the lowest floor of a hospital not on the patient rooms floor. And the blinds on the windows would certainly be closed. In this hospital they are open and people can see dead bodies. Never happen.
Factual error: It is not possible to have a conjoined twin of the opposite sex. They are similar to identical twins, which are always of the same sex, in that they are formed from a single zygote. In the case of conjoined twins, the zygote fails to divide normally.
Suggested correction: There are always exceptions to the rules and, although VERY rare, it IS possible for conjoined twins to be - rather, end up being - different sexes. There are about 10 documented cases. In one case, is my understanding the conjoined twins started out as males but a genetic mutation (or something) occurred and one male lost his Y chromosome, thereby developing into a female with no ovaries. (The now-female twin would have so-called Turner Syndrome.) I don't have any sources to quote off-hand.
The male would have lost his Y chromosome after the zygote "split", but he was a monozygotic male.
Factual error: There is no way in hell they can carry $200,000,000 in cash (over 4,000lbs), let alone load it on the helicopter.
Suggested correction: They never did and it was never the idea. They simply didn't figure out it's not physically possible. They took as much as they could from the vault in the much more limited time they had, and never got any of it to the helicopter (except for 1 small stack) anyway.
It's true that the team was not meant to recover all the money, but they didn't know that going in. How did Ward and Peters, who seem reasonably smart, not consider the weight when planning the heist? The deal Ward believed was "get paid $50 million to recover $200 million" not "grab what you can and good luck"
I suppose it could be counted as a stupidity, but I'm not sure anyone is really aware of the weight of 200 million in cash, even reasonably smart people. Never seen it, never weighed it.
Factual error: When Ed and Lorraine Warren are trying to convince the lawyer to represent Arne, there are is a copy of "Jonathan Strange and Mr. Norrel" on the shelf behind them, which was published in 2004. The film is set in 1981.
Factual error: There is a calendar in a scene towards the end of the movie which shows the date as Wednesday April 30, 2021 but the calendar does not align to the days of a real calendar. That date will be a Friday. (01:25:54)
Factual error: On Saturday morning Gwen and Finney were watching cartoons. This was the day after she spent the night at her friends house which was a Friday night. The cartoon that was on the TV was Davey and Goliath. This cartoon only aired on Sunday mornings.
Suggested correction: "Davy and Goliath" aired on Saturday or Sunday mornings, depending on the TV station. And, according to Wikipedia, it "premiered in syndication on 2/25/61 as a Saturday feature."
Factual error: When we see Young Shriek struggling with Young Detective Mulligan, the gunshot explodes when the weapon is pointed up and at distance from her face. Obviously a direct shot to her eye socket would have killed her, but she is blind in that eye and has a scar in two distinct parts of the socket. It's hard to imagine how a wound with that pattern could have occurred even thinking of the bullet ricocheting off the top of the trunk or something. (00:02:55)
Factual error: Teenagers Claire and Fiona would have been carded and not permitted to enter the "Saints and Sinners" bar because they were under age 21, but they were able to sit at a table and get served alcohol. (00:51:37)
Factual error: A body-sized floor-length mirror angled away from a wall would not be able to capture a mirror image of that wall or objects on or close to the wall (e.g, drapes, clock, table, etc). (00:06:16)
Factual error: The initial police scene takes pace 20 years ago. The present year is 2021, so 20 years prior would've made it 2001. The police Chevrolet Tahoe at the opening scene of the film was only made from 2007 and up. (00:05:40)
Factual error: When pit bull Shadow was chasing Phoenix, the distances between them varied - even appearing to increase - but the pit bull should have been able to quickly close the gap and catch Phoenix. In general, an adult person (about 7 mph) cannot outrun a pit bull (25-30 mph). Also, unless Shadow was trained to stop pursuing Phoenix if she got over the fence, pit bulls are actually quite good at climbing fences. (00:02:38)
Factual error: Charlie gives Kaz a flare gun to shoot a shark in the mouth underwater. She manages to fire it underwater and the flare travels several meters. It is impossible for a flare gun to activate underwater. And if the flare was fired into the water it will only travel one or two feet. (01:13:00 - 01:18:00)
Factual error: When Sharyn woke up after surgery, she did not know how long she had been there, but her abdominal scar was practically healed. Under these circumstances, she should have had a urinary catheter but did not. Also, when Sharyn lifted her gown to look at the scar, she was wearing bikini-like lace-trimmed navy blue underwear - it is unlikely anyone would have put such underwear on her after surgery. (00:05:14)
Factual error: One of the sisters threw a bucket of water over the dock to wash away the blood. Seconds later, the dock was dry. Even with the sun shining, wood does not dry that fast. (00:10:03)
Factual error: Paul made a big deal out of son-in-law Jeff getting the New York "brownstone" [worth several million dollars], but an exterior view of Jeff looking out a window shows he is NOT in a true brownstone. This must be an end unit, but a brownstone should have all brick on the exterior side - not brick part-way and cement blocks the rest of the way. (00:38:39)
Factual error: Despite the film being set in the 1990s, many cars made after 2010 appear in street scenes. (00:25:00 - 00:25:30)
Factual error: The crow (mechanical at least in part) perching atop the dead tree lacked some details/behaviors that would've been displayed by a real crow. Its tail should have been thinner and longer (not short and wide, although they do fan). It would have repeatedly cawed upon noticing Geary and Fenn approaching to alert family members of potential danger. It would not have straightened its head to watch the men; the dominant eye would be used to see better (monocular vision is better than binocular). (00:04:40)