Continuity mistake: The case files which Agent Cowles brought to the kitchen and put on the countertop disappear shortly after being placed there. (00:08:30 - 00:09:10)
Continuity mistake: When Frank Walker and Casey Newton get into Frank's bath to escape the robots, Frank gets in on the left and Casey gets in on the right. They get shot off but when they land in the swamp, Frank is on the right and Casey is on the left.
Continuity mistake: When Shaggy and Scooby are approaching the Demon as he eats, it is shown that he is eating from a platter of hamburgers and french fries. Scooby and Shaggy bump into his table, knocking the food all on the floor. When Shaggy and Scooby quickly put all of the food back on the table, it now has french fries and hot dogs.
Continuity mistake: When Albright's driver is taking Mark at gunpoint to the car (after leaving Mrs. Jensen's room) he has his gun against Mark's chest, but in the next shot it's against his back.
Continuity mistake: When Gordo leaves Simon and Robyn for a few minutes to handle a work thing, Simon starts mocking Gordo in his absence. Simon tells Robyn that Gordo wants to nail her and Robyn says "Stop it," but Simon continues his mocking of Gordo. At the end when Simon is listening to the recording that Gordo made of that conversation, Robyn's "Stop it" is absent.
Continuity mistake: Inspector Maggie Price arrives on the crime scene; the first time we see the coroner near the body, the left hand of the deceased has just a tiny bit of tablecloth underneath it. It has a much larger portion in the overhead shots that follow. (00:18:30)
Continuity mistake: Maggie shows the article about Evelynn's husband holding the phone in her left hand in close-up, which is not how she handles it in the previous and following shot. (01:04:20)
Factual error: Michael's wife meets with Longo in prison, and she has an iPhone. The trial was in 2003, 4 years before the introduction of the iPhone in 2007.
Continuity mistake: SPOILER: The boy, Roger, finds a glove in a secret drawer in Mr. Holmes' room. The glove is lying perfectly flat in the drawer. It had supposedly been there for years unknown to Mr. Holmes. Later, in a flashback scene, it shows Dr. Watson putting the glove in the drawer. When he puts the glove in the secret drawer, it is not laid flat in the drawer - it has an obvious upward bend in the glove. Since the glove had been in the drawer, untouched, for years, it should have still had that upward bend.
Suggested correction: Although we are only shown Watson putting the glove in the drawer once there is no reason to suggest he may not have looked at it again before he left for good. More compellingly, Watson placed the glove in the drawer whilst the bureau was in place in Holmes' quarters in London, and it was not discovered until a quarter of a century later having been moved at some point to Holmes' house in Sussex. This journey could also easily have displaced the gloves position to some degree. The weight of papers contained in the drawer above may have also aided in flattening the glove out over the years.
Continuity mistake: When the boys are about to enter the woods and they arrive on their bikes, the younger boy can be seen first on his bike, then standing next to his bike in the next shot, then on his bike, then he's off it again where he lets it fall onto its side.
Visible crew/equipment: When Matthew is following Nina's cries for help through the woods you can see numerous set lights in between the trees (in the distance). (01:09:43)