Factual error: When Dexter and Doakes are looking at the severed foot wearing a soccer cleat, Dexter states, "The foot was severed between the tarsus and the metatarsus." However, the foot was severed proximal to the tarsus, through the tibia and fibula. The cut was easily too high to be between the tarsus and metatarsus. (00:16:45)
Factual error: When Gwen finds Toshiko's hidden message from 1941, she realizes that it was written in blood, and her flashlight reveals the bright red letters on the now-yellowed piece of paper. But after 60+ years, the iron in the blood would oxidize. The writing on the note should be rust-brown, not red. (00:33:40)
Factual error: When Emma freezes the water in Elliot's shower, frozen water continues to fall on Elliot. This is not possible because Emma only froze the water Elliot was using. Water would still come out of the shower head, but ice comes out instead. Arguably, Emma could be freezing the water in the pipes, but if she did that, nothing would come out of the shower.
Factual error: Shawn reports that one of the attendees of the speed dating session drives a 2004 Trans-Am. The Trans-Am was discontinued in 2002.
Factual error: In the episode where Kyle, Lori, and Josh first go to the pool together, Kyle jumps off the diving board, but he's only in the water for about three seconds before he sees Amanda, who is already swimming toward him. This means that he was in the water for just a second or two before she jumped in. That isn't enough time for anyone to appear to be drowning, especially to a trained lifeguard like Amanda.