Continuity mistake: When Hagmaier is in the Florida State Prison room waiting for Bundy, his hair changes. Initially, his short bangs are straight across the middle of his forehead. When Bundy sits down, Hagmaier's bangs and top of head are "fluffier" (perhaps blown dry) and combed to the side. (00:11:05)
Factual error: Unless left in the vehicle (not the case here), towed impounded vehicles do not have keys. Moreover, lacking keys, a valid registration, possibly proof of insurance, and new plates, vehicles bought at a NYPD auction are to be TOWED away. A newly-purchased auctioned vehicle, such as the Navigator in the movie, is "ticket-" or "citation-ready", not ready to be driven on the streets.
Revealing mistake: DEA Agent Rick Bowden was already seated "in the best position" before knowing where Ross would sit in the SF library. Chris Tarbell already had a surveillance camera behind the seat Ross chose, giving him a clear view of Ross, also before knowing where Ross was going to sit. Even if there were cameras in other positions, the DEA Agent and Chris Tarbell being at the right spots in advance was too coincidental to be by chance alone. (00:02:09 - 00:02:30)
Factual error: After Ressler tells McChesney he wouldn't be surprised if one day she's tracking down sequence killers, McChesney replies, "Not sequence killers. Serial killers. That's what they should be called." But it was Ressler who claimed he coined and is often credited with coining the term "serial killers" (at least in the U.S). ** After showing pictures of some of Bundy's victims, Ressler is shown and it is pointed out, "He [Ressler] is credited with coining the term 'serial killer'." (1:31:30). (00:26:40)
Continuity mistake: Joe has 'Rick C' (his partner) listed as a contact in his phone - late on in the movie when Joe calls him from the bathroom stall, he is listed as just "Rick"
Revealing mistake: The "bridge" within the crime scene tape is obviously a prop. It should be a continuation of the road, but it is tilted to the left and is more vertical (around 45°). The bridge isn't even very high. When Byron and others go under the bridge to look at the dead girl, there is only a few feet above their heads (clearance under the bridge). (00:04:54)
Revealing mistake: The "unnatural seam" (line) across Jimmy's forehead and beyond - as well as the overall appearance of his head - indicates that he is NOT "naturally bald"! His "fake" bald head was not put on nearly as well as those seen in numerous other movies. [The actor playing the character does not have much hair in real life, but he also doesn't have that artifical line across his forehead.]. (00:07:13)
Character mistake: After banker Karl was reported missing from his home, the police detective did not even think to locate his car - which he could have merely driven away in (meaning he was not kidnapped).
Revealing mistake: During one of the chase scenes, an SUV hits a rock barrier and flips over landing on its top. The car spins around, and we see that it is empty. The driver then climbs out as if he was just in the vehicle.
Other mistake: The issued sidearm for the Spanish National Police is the H&K USP 9mm Compact, which has a capacity of 13+1 bullets, and the Civil Guards' is the Beretta 92fs/M9, which is a 9mm and has a magazine capacity of 15+1 bullets. As of 2020 the Beretta is being phased out for the H&K USP C. The police officer fires a total of 5 bullets from his Beretta then the slide locks back because its dry. He has no magazines for reloads either. I highly doubt the Spanish police issues 5 bullets to their officers. (00:33:00 - 00:35:30)