Plot hole: In the first film, the shape of the ring was a little different and it was set in a ring. Also, it was given to Xania. In the second film, she was never even acknowledged as donating it to the museum.
Plot hole: While breaking into the vault, Gabe and Ripley use a reciprocating saw to cut a block from the concrete wall. The block is several feet thick, quite beyond the reach of a saw of the sort. The view after the block is cut also shows no holes where they would have had to drill to get the cut started. (00:56:00)
Plot hole: Van Ryberg is told that the terra forming plant had C4 laid everywhere, and that it just needed someone to go in there and set it off. Firstly, what Van Ryberg finds is dynamite, not C4, and he also tells Madison and the Doctor that they only have ten seconds to get out. If the timer was already running, then there was no need for anyone to go into the plant to set off the explosives.
Plot hole: According to the phone book the name given was "M. Horowitz" but when Mary mails he first letter to him she already knows it's "Max."
Plot hole: Every ghost that we see in the house looks the way they did when they died, for example the girl from the film's intro is seen without skin on her face, which happened to her before she died. However, in the final scene when we see Simon's ghost joining them, he looks completely normal, when he should have had a throat slit wound and the carved markings on his skin. (01:31:20)
Plot hole: During Ed's transformation back to humanity, he burst into flames several times. His heartbeat was monitored using wires attached to his chest. They did not stop working despite being in the flames.
Plot hole: The main character never takes the elevator. He only takes the stairs. When leading a workshop he leads a group of people from street level by saying 'follow me' and in the next shot the whole group is on top of a high rise hotel. How did he and the entire group get from street level to the roof together if he never takes the elevator?
Plot hole: In the series we learn that these creatures take a lot longer than us humans to grow up and that they live a lot longer. They mention that the children are about 900 years old, so a grown-up would be more than 1000 (probably 2000). The series is set around our time (1990s/2000s) and Fjellrose and Erke are very old. Yet the film is set about 100 or 200 years ago, you can tell by the way the humans are dressed and the way their houses are built etc. So Fjellrose and Erke should still be grown up, but they are young children. If they are only 100 to 200 years younger, then they should be much older in the film or much younger in the series.