Continuity mistake: The left tail light of Sadie's car is broken when she picks up the unfortunate hitchhiker. The light works when she turns left off the road. (00:36:20 - 00:38:35)
Factual error: Right after Walter has the nightmare about killing his wife, he wakes up and turns around to see the alarm clock show 11:12. The clock makes a flipping sound when it switches to the next minute, just like those alarm clocks from the 1980s that have those little numbered plastic cards inside. However, it's a digital alarm clock and they do not make such sounds.
Revealing mistake: Sean Patrick Flanery plays a nerd who has trapped a female vampire in a cage. About 3/4 of the way into the movie, he tricks a co-worker into visiting, planning to feed him to her. He extends his right arm through the bars, and she starts to caress and kiss it, then begins to bite it and suck his blood. When he tries to withdraw, she tears off his arm at the shoulder. But in the next shot, he and Flannery both hit the floor outside the cage, and the co-worker's right arm is visible. However, when the scene begins, both Flanery and the co-worker are wearing watches on their left wrists, and in the shot of them on the floor, both have watches on the right, suggesting that the image has been reversed.
Continuity mistake: After arriving at the mountain cabin, Terry comes in to the bedroom and notices Diane has fallen asleep while working. At first, her laptop computer is screen-up on her lap with the stylus in her hand. But just before Terry leaves, the laptop is screen-down and the stylus is gone.
Continuity mistake: When Sarah is on the beach in a gown and slippers, she takes the slippers off, then they are back on, then seen off, on the sand, again.
Continuity mistake: All wide shots of Hrothgar's hall show it in the outer ward of his fortress, about two hundred metres from the towers on the edge of the cliff, with open ground on three sides and an embankment on the fourth. But later several characters are able to step straight out of the hall onto a balcony that overhangs the cliffs and sea below.
Other mistake: At the end, during the neighborhood fight scene, Monty is punching Joe, but you can clearly see that he is not actually coming in contact with Joe's face.
Factual error: When the two nuns strip to join Lorenzo in the bathtub, they both have bikini tan lines, hardly an everyday occurrence during the 14th century.
Continuity mistake: When Richard and Nikki get caught in Teddy's apartment the sweater that Nikki is wearing keeps changing from being zipped high to zipped low.
Revealing mistake: In the jazz club, the saxophone player's finger movements don't match what he is playing.
Revealing mistake: When Billy is looking at Nick's driver's license, for sex it says F for female.
Continuity mistake: After hitting the animal in the forest when entering the park, the windscreen of the van is covered in blood. In the next shot the van is shiny and looks like it has just been washed, but a few seconds later it has dried blood on it again.
Factual error: During the scene where Captian Less finds out his father was sent to Auschwitz by Eichmann, one of the maps on the wall displays a map of Europe. The map, however, is incorrect, and is a modern day map as opposed to how a map would have looked in 1961. At the time, the Czech Republic and Slovakia didn't exist as separate entities, Germany was not unified, Yugoslavia was yet to dissolve and Ukraine, Belarus, Estonia, Latvia, Lithuania and Moldova would not have appeared as separate states. (00:43:45 - 00:45:35)
Continuity mistake: In the scene where Mackenzie's father is at the grill BBQing, you see a remote control in his shirt pocket. The remote control disappears and reappears in several shots.
Other mistake: Just before Debbie takes her shirt off after Walter has given all of the Playpen girls suggestions, one of the girls says "It's hot in here." (probably Debbie, but it doesn't really sound like her), but Mona doesn't start having an orgasm, when "in" is supposed to start it. (00:33:50)
Continuity mistake: When the girl is looking up the fire engine in the oversized book, the little blonde boy in the red T-Shirt on the stool next to her changes the position of his head and hands between shots as she brings the book to the desk.
Continuity mistake: When Vivian is walking to meet Aiden for their date, Vivian's dress changes from black to brown.
Continuity mistake: When Nicole breaks the glowstick and splashes the liquid on the killer's mask, she starts to run. In the next shot of the killer, there is no liquid on the mask, yet it reappears in subsequent shots. (01:03:20)
Revealing mistake: After Steven Wilkins disguised as a vampire kills the unnamed woman he closes her eyelids to make it look like she's asleep. Just before his hand contacts her eyelids you see her almost blink, revealing she's very much alive.
Factual error: When the wraiths first invade the stockade, one of the officers orders his men to fire their "rifles". This is the 16th century. They're firing muskets.