Revealing: In the scene when the main character is in the library on the internet, she goes to a couple of websites. When the shot shows the URL up top, it is C:\windows98\mydocuments\etc.html. Instead of actually searching on the web they used a premade html page and accessed it from their computer. It's simple enough to just not display the address bar in your browser, so I don't know why they let this one slip through...

Other: For some reason, there is no "correct entry" option. I thought I'd do it like this. The well extends above the ground some feet. It is mostly in an open field: therefore, no shade cast upon it. As long as the top surface of the well is not PERFECTLY flat and the bottom surface of the cover is not perfectly flat, there will be gaps that light can enter all the way around. You can experiment with a tube of any kind and a lid to fit. Just rough up both surfaces. Place the tube over one eye, close the other, point the tube to the light and slide the lid on. You will see a ring.

Visible crew/equipment: In the scene where Noah breaks into the mental institution's record room and is looking through Anna's files, there is a visible arm with a blue sleeve to his right, even though he is alone.

Continuity: Samara, as seen in the psychiatric sessions on the videotape, has a prominent gap in her front teeth - yet when she decomposes in Rachel's arms down in the well, the skull that is left has perfect teeth with no visible gap.