Character mistake: The prosecuting attorney told William, "In the interests of getting this thug [Danny] off the streets as soon as possible, his attorney has agreed to plead guilty to assaulting an officer, possession with the intent to distribute, and resisting arrest, and that's all in addition to his parole violations. We're looking at five to seven [years in prison]." The parole violations alone are sufficient to get Danny off the streets immediately. (00:09:34)
Character mistake: John would have no reason to ask the CT technician if she had any results. He says "that was a long one," indicating he's had this done before and should know it typically takes around 24-48 hours to get results. (Likely just a line of dialogue added for the benefit of the audience, who may not know.)
Character mistake: When John meets his clone in the rundown house he lives in, the clone has a British accent and tells him his story. John has an American accent. When the real John tells him "I'm not like you, I had a wife, a family, a daughter" he mistakenly uses a British accent.
Character mistake: When Annie is in the red truck, she says that she'll be cooking for ten staff. When Alice goes to the beach, she tells Bill that everyone has arrived except for Annie. Even if she had arrived, there would only be eight of them: Christie, Annie, Ned, Brenda, Jack, Marcy, Bill, and Alice. Two shy of what she told the truck driver.
Character mistake: Zoe states that Lilly's condition is very contagious and will spread through the camp if they don't go out and get the proper medical supplies they need. She puts Lilly in quarantine... and then proceeds to visit Lilly with no protective equipment. No mask, and even touches Lilly with her bare hands before going back out to the rest of the people. (00:19:20)
Character mistake: When Leon goes to see Susan Hoff with his photography portfolio she tells him he needs improvement. After she leaves, Leon tells Jurgis that he thinks she hated his work and Jurgis tells Leon "when she hates somebody's work she gives them about a minute, you got three." In reality, she actually did give him one minute almost to the second. (00:06:58)
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: We see the lead driving on the motorway to get to the cottage. She leaves at junction 6 for Princes Risborough. Which means she is on the M40 that goes to Birmingham. When she arrives the host asks about the drive down and mentions the M4. This is a different road entirely, that goes to Swansea.
Character mistake: When they're making the protection circle they make a star of David and not a pentagram, 6 points in a star vs 5 points.
Suggested correction: I don't think there was anything in the movie that dictated a pentagram had to be used. In the book of protection rituals they were using, the particular ritual showed a picture of the star of David they needed to create, so that's what they used (plus salt).
To add to the correction, what the mistake refers to as "Star of David" is a hexagram and the use of hexagrams in the occult are not uncommon. You can find salt protection circles that use the hexagram.
Character mistake: When Cain is attempting CPR on the flatlined patient at the beginning of the film, he tells the other doctor, "She just needs a little more time for the drugs to circulate." Circulation stops at the moment of flatlining. (00:05:25)
Character mistake: When Harrigan is watching the surveillance video by Bill Paxton he states that the helicopter is a silver Alouette when it is actually an AS-350.
Character mistake: Roy says, "He thinks the wounds look self inflicted." But the doctor who said that was a female.
Character mistake: When Duddit's mom is packing his lunchbox, she refers to him as "Henry". (01:45:54)
Character mistake: Doreen/Mom told Rose she'd be back from the store "in a jiffy." Rose asked, "How long is a 'jiffy'?" and Doreen replied "in about an hour." "Jiffy" typically means VERY fast (perhaps as short as a nanosecond) and, even if people have different perceptions of how much time a "jiffy" is, an hour is excessive by general standards and does not reflect its true meaning. (00:32:50)
Character mistake: When Dr. Elkins is measuring the Killer Whale, she says "111 centimeters" followed immediately by "68" (centimeters). But her arm spread shown when she says that is not 111 centimeters - about 3.6 feet (1+ YARD wide). It's more like 2 feet. The "68 centimeters" is actually more accurate for the shot though: 26 inches, which is shown.
Character mistake: When the second fog bank rolls in, the weatherman says it is coming from the south-east, and the DJ says the same thing once; the second time, however, she says the south-west.
Character mistake: When the main character follows the Dutch businessman down the stairs (the same scene the girl with the white jacket and white bag walks downstairs before we see her walking up the stairs) there is a commercial which reads "JETZT AUCH AM DVD" which is wrong and should be "JETZT AUCH AUF DVD." (01:22:45)
Character mistake: In the very first scene, in the first shot you see a sign in Spanish that says "NO PASE por orden del departamento de arquiologia". The correct Spanish word is arqueologia.
Character mistake: When nurse McTavish checks mum's pulse, she uses her thumb. Any nurse worth her salt knows that thumbs have their own pulse and that one needs to use the index and middle finger to get an accurate pulse. (00:30:10)
Character mistake: The little girl asks Kristen "what's your name?" Kristen replies "Kirsten". (00:05:59)
Suggested correction: I hear her say "Kristen." The transcript and subtitle even say "Kristen."