Character mistake: Barbara is in her office looking for the one item they need help to identify when Diana walks in. She says "OK, item number 23." She suddenly finds it saying "here it is" and reaches in the box to grab the Dreamstone. The ticket says item #24. (00:22:18 - 00:22:50)
Character mistake: The protagonist says "You know, Croesus once said 'Count no man happy until the end is known'" but it's not Croesus uttering that line. According to Herodotus, Solon says it to King Croesus. (00:03:00)
Character mistake: A radio report refers to a character with two different police ranks with 15 seconds apart in the same broadcast - first as a Police Chief and a few seconds later as a Captain. (00:21:28)
Character mistake: Flight Lieutenant Williams is addressed as "Lieutenant" a couple of times. RAF (or RNZAF) flight lieutenants are always addressed by their full rank.
Character mistake: NYPD officers have their guns drawn toward the elevator in the Carrington Hotel. When the door opens, Borz, wearing an unbuttoned Carrington jacket - but not the hat or white gloves that the doormen wear - is told by an officer to "hold it" and states that he's "just a doorman." The officer backs up and allows Borz to leave. A police officer would not simply accept the word of anyone in this situation. The person would be handcuffed and detained until the situation is under control and the police determine he was not (or was) involved. (01:24:41 - 01:35:02)
Character mistake: The new sheriff ("Alice") told Rayburn that she has only been sheriff for a couple months and was still catching up on active cases. Rayburn replied, "Yeah, my daughter's case is far from active." The sheriff then told Rayburn, "My training is very different from the officers around here" - meaning college-educated (Ivy League?), more professional, more effective, and modern. Despite this, some of the sheriff's actions (e.g, walking unannounced into suspects' houses and/or without a proper warrant; questionable "probable cause"; shooting Rayburn to protect her brother) fell far short of the ideal. Perhaps most significantly, the sheriff gave Rayburn a warning shot and told him not to kill Dr. Boone... then she stood back and merely watched Rayburn push Dr. Boone into the pitfall and close the doors while knowing the doctor was severely injured and dying. These things do not show her purported superior training. (00:21:43 - 01:25:34)
Character mistake: Whenever a YouTube livestream by jacksepticeye is shown, his name in the URL is misspelled as "jackspecticeye," and his username is spelled with a capital J when it should be a lowercase j. (00:30:16)
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: The movie is set in 1999. Mike's ex was arrested on November 11, 1995. Mike then tells Marcus that he met her when he was an undercover cop in Mexico, fresh out of the academy, "twenty-four years ago," before he got partnered up with him. However, earlier in the movie, it's mentioned that Marcus has been married to Theresa for 26 years and partnered with Mike for 25 years.