Continuity mistake: The land mass where Ty first spots the gold coin is different from the area he picks it up at. During the first camera shot watch the waves coming in. The waves do not even go over the coin. Stick around to watch some poor film editing because you can see the coin turn into a board just before a wave covers the coin. (00:24:45 - 00:25:50)
Plot hole: When the fog finally hits the lighthouse and is seeping in, the generator is hardly audible vs. how loud it was when it was first started.
Continuity mistake: At the beginning of the movie there is a shot showing the setting sun in the distance even though it's supposed to be just after midnight.
Audio problem: When the zombie guys are breaking the windows at the church, you can hear multiple pieces of glass hit the ground even though almost no pieces fall.
Deliberate mistake: When Jamie Lee is picked up hitch hiking, the view out the front windshield, while pulling over to pick her up, is identical when they pull over moments later after all the windows are shattering.
Factual error: A solid gold cross of the size used in the film would weigh more than what any human could hold in front of them (nearly 200kg), much less as "easily" as the priest did at the end of the movie.
Continuity mistake: After the glass breaks all around the pick-up truck the camera gives you the viewpoint of the two riders looking through (what used to be) the front windshield. Initially, there are many shards of glass still sticking in the frame. When the two riders look through again there is less glass in the frame. (00:14:00)
Revealing mistake: The door to the weather observatory shows that it is a set by the lack of a complete door frame at the bottom which would let rain and other elements in under it.
Continuity mistake: When 2 women turn station wagon to visit Father Malone (1st time), the hidden headlight doors are up, showing headlights. Lights are off so the doors should be down. Next scene pulling up to the church and getting out, the doors are closed.
Continuity mistake: When Stevie puts the piece of driftwood down on top of the tape rack water is already moving along on the table even though the water hasn't begun dripping from the driftwood.
Continuity mistake: The scene where they show the gas station's nozzle, while it is mounted on the pump has a trigger. When the nozzle falls to the ground, even in the position that the camera is filming it, the trigger should still be visible, due to the fact that one should still be able to see the tip end of the trigger protruding through the opening at the bottom of the nozzle, thus allowing the automatic trigger holder to come in to contact with it. However, the trigger is no longer present. (00:10:15)
Other mistake: After rescuing the boy, Jamie gets the 1946 Ford truck stuck, having rounded vent window frames. But inside as she tries to move the truck we see "dogleg" vent frames from say a 1963 Chevy truck (more pointed, angled back).
Continuity mistake: When Stevie Wayne is in her studio and the wood from the Elizabeth Dane starts leaking, there is a clock very prominently in every shot of her. The time constantly jumps back and forth, and in one section it jumps 5 minutes forwards in just two seconds of continuous action on-screen. (00:45:48)
Visible crew/equipment: At the bar, Nick says to Liz "I'll be right back" and there is an immediate cut to the front of the lighthouse. Just before the fog begins to roll in you can see a crew member on the left side of screen moving around. It looks like he was signalling for the fog to be poured in. (00:53:24)